Xr400 Faq

[spenx75]

Lenghty but with good info. . .

 

  Quote

The Honda XR400R Frequently Asked Questions - by Paul Gortmaker

 

 

Last updated: October 15th, 2004.

 

This document contains the following sections:

 

-Introduction

-Miscellaneous Questions and Answers

-General de-restricting or Uncorking

-Carb Questions

-Maintenance Issues

-Engine Questions

-Chassis and Suspension Questions

-Electrical Questions

-Other Modifications

-Part Numbers

-Changes and Upgrades Each Year.

 

------- Introduction --------

 

The Honda XR400R was first released as a 1996 model. It has survived to

2004 with fairly minimal changes, and yet continues to sell in significant

numbers. In the beginning there were people who were even racing them MX,

but as technology has advanced, the 400 has taken on the role as a very

popular trail bike. Ask most people what they like about the 400 and

chances are the most common answer will be the stone axe reliability.

Hovever, it appears that the end for the 400 is now here, as Honda have

announced that they are stopping production in March 2005.

 

You should have got the owners manual with your bike. It covers basic

things like checking the oil and oil changes. If you intend to do any

mechanical service to your bike by yourself, then you should invest in

the official service manual for the bike. It has all the tolerances,

torque values, and (dis)assembly instructions. If you have the desire

to learn a bit about how the bike works and how to fix things then the

Honda Common Service manual goes more in this direction, without

getting into the more bike specific details. You might be able to

save some money by finding a used manual. If not, then you can order the

manual directly from **** Inc. who prints them. Ordering from **** is

usually cheaper than going through your dealer if you are in the USA.

There is a page in the back of your Owner's Manual that tells you how

to order from ****, or do it online at: http://www.helminc.com

 

While the answers to some Frequently Asked Questions that appear here can

also be found in the above manuals, note that this document does not

attempt to cover even 1% of what is in the manuals, but rather to list

those things that can't be found in the manuals.

 

While every attempt has been made to ensure this document is as accurate

and as useful as possible, note that THIS INFO COMES WITH NO GUARANTEE

OF ACCURACY OR FITNESS FOR ANY PURPOSE WHATSOEVER - USE AT OWN RISK.

 

 

-------- Miscellaneous Questions and Answers --------

 

Q: What does the bike really weigh?

 

A: Honda claims 257 lb dry, but typically 265 lb, ready to ride, no gas,

with the difference being from motor oil, suspension oil and brake fluid.

 

 

Q: How much gas does it hold and what range will that give?

 

A: Honda says 2.5 US gal (9.5 litres), but 10 litres will fit with the white

plastic inner tank neck removed. The range depends on how tight the trails

you are riding and the gearing (sprocket choice) you are using, plus

whether the carb has been re-jetted. The best case scenario, that being

with dual sport gearing (16/40) and a lot of top gear use with a high

average speed will get you 24 km/l for a range of 220km (135 miles) on

a re-jetted bike at sea level. With stock gearing and use on slow goat

trails, your range can be reduced to half of that. Note that the reserve

capacity varies greatly with the terrain you are riding on, as a smooth

surface will not slosh fuel over the hump to the side with the fuel valve.

 

 

Q: What is the HRC kit and what does it contain?

 

A: HRC is the racing branch of Honda - in 1996 they offered the engine

power up kit for the XR400. If you dig around the Yahoo 400 group

archives, you can find a test on the HRC kit from an old bike magazine.

 

The full parts listing of the HRC kit and the individual part numbers

can be found in the "Part Number" section of this document. To summarize,

it came with a camshaft, a higher compression piston, a different crank

gear and clutch basket that changed the primary reduction slightly.

(Stock 23/65=2.826:1 and HRC 24/64=2.667:1) To get a feel for that

gearing change, you would have to run a 48 tooth rear sprocket with the

HRC parts to get the same overall reduction as the stock parts give with a

stock 45 tooth rear sprocket. Other small parts included gaskets, jets,

clutch springs and a setup manual.

 

 

Q: I think I want the HRC power up kit, but do I need all the pieces?

 

A: Here is something you may want to consider: Back when this was

introduced (1996) some hopped up 400's had transmission failures.

To help alleviate this, the HRC kit shipped with a new crank

gear and clutch basket that changed the primary reduction

slightly to reduce strain on the transmission.

However, Honda has upgraded the 2nd gear set and in 1999

they upped the diameter of some of the tranny shafts by 1mm,

since several shear failures had been reported (yikes!)

 

What I'm getting at is that if you have a 1999 or newer bike,

you may want to consider ordering individual HRC parts and

not get the clutch basket and crank gear. People with 1999

and newer bikes are doing non-Honda hop ups (440 kits,

aftermarket cams, hi-comp pistons, etc.) and the stock trans

doesn't appear to be a weak point anymore.

 

Other parts (like the carb needle) are also redundant if you

have a newer non California bike. You can probably narrow

down the list of main and pilot jets too.

 

 

Q: What are some of the other non Honda hop up parts people are using?

 

A: There are various bigger displacement kits, ranging from 416cc up to

440cc. Some require a cylinder bore, and others re-sleeve your cylinder.

In either case you are replacing the piston as well, and can choose the

compression ratio. At the risk of over simplifying, the compression ratio

is just how much the gas/air mixture gets squished down to at the top of

the piston travel when compared to the volume it was at the bottom. A

higher compression ratio generally means more power, but also requires

better quality fuel. Stock is 9.3:1 and the fuel requirements are pretty

relaxed. Something like 13:1 is getting extreme and will require expensive

race fuels to prevent engine damage.

 

There are also aftermarket ignition modules available - these change the

power output by changing the time at which the spark plug ignites the fuel

air mixture. An earlier (more advanced) ignition can give more power, but

if you try and run too much ignition advance uncontrolled combustion can

occur which you can hear as a pinging/detonation and this can lead to

piston and engine damage. Rumours are circulating that one of the

aftermarket ignitions is just a re-badged xr250 ignition, which apparently

has a different advance curve and a higher set point for the rev limiter.

In 1998, the North American XR400 got a different ignition curve (see yearly

changes section), presumably to work with the leaner jetting and emissions

standards, however European bikes still get the older one.

 

Replacement of the stock carburettor with one of the "pumper" carbs seems

to be a popular part to buy. These carbs have a small pump arm built in

that gives an additional squirt of fuel to the motor whenever the throttle

is moved from the closed to the open position. This gives people the

"instant on" throttle response without any bog or hesitation that can

happen when the throttle is opened quickly on the stock non pumper carb.

 

Finally, there are lots of various exhaust pipe and complete exhaust system

manufacturers out there that want to sell you a lighter and most likely

louder exhaust pipe. Be sure that any pipe you are looking at will pass

the appropriate sound test for the areas that you ride in.

 

 

Q: How do the bikes for various countries differ from each other?

 

A: Besides the yearly updates, there are also some minor differences in

the bikes depending on which country or region it was originally shipped to.

Non-US bikes are coded ED for Europe, CM for Canada, and U for Australia.

Variations within the US bikes exist for California models as well.

 

The biggest difference is that bikes outside of North America have more

elaborate lighting systems and are street legal right off the showroom

floor! Yes, the ED and U bikes have a bigger Hi/Lo headlight, optional

turn signals, a full speedometer with odometer and a dual electrical system

with a dual output stator (electrical generator). One half of the stator

feeds AC to the headlight, and the other half is converted into DC and used

to run all the other accesories (turn lamps, brake light, horn, etc.)

Note that the "bigger" headlight is just that - physically bigger. The

bulb is apparently still only 35W on either filament. It seems that the

later UK versions don't have the turn signals or horn mounted as well.

 

The factory carb jetting also seems to vary depending on whether the bike

was A/CM, ED/DK or U, with the U bikes getting the leanest setup.

 

 

Q: What are these "Gordon Mods" I keep hearing about?

 

A: Gordon used to frequent one of the XR400 internet discussion groups.

Being a writer by trade, he took the time to type in the steps he took

to de-restrict his bike, since it was asked so often on the discussion

group. Rather than re-type it all in, people just kept sending copies

of Gordon's original modification list to the newbies when they asked.

Hence it took on the unofficial name "Gordon's Mods". People are

still sending it back and forth even though Gordon sold his 400 years

ago and last I heard was enjoying time with his wife on a GoldWing.

De-restricting the bike is covered further on in this document.

 

 

Q: Is there any other sources of information?

 

A: John Rushworth put together some stuff that covered the first few years

of the XR400. It had some good information in it, but it hasn't been

updated since 1998, as John had moved on from the XR400. Fortunately John

kept it available as a convenient Zip file. Do a search on his name and or

"XR4FAQ_26Stuff.zip" and you should be able to find a copy somewhere.

 

 

Q: Is the engine the same as that used in the TRX400 quad?

 

A: It shares a lot of parts with it. But the quad uses a milder camshaft,

and has different cases and crankshaft to accomodate the electric start.

It also uses a different carb, and ignition (CDI/flywheel).

 

 

Q: Why does my kickstart have a little triangle on the side of it?

 

A: On early 400's, you would see people complain about the kickstart

flopping out on them while riding. If you move the kickstart backwards

without folding it out, you will see that the triangle contacts the frame,

and probably the paint is even wore there already. If that triangle

wasn't there, the kickstart would continue back and the frame would swing

it outward at the same time. What you should really be asking is why

does the kickstart need to be labeled "KICKSTART" - is anyone really

that stupid?

 

 

Q: What are the torque values for the fork tube pinch bolts?

 

A: For some reason, the 400 service manual does not list them. But if you

look in say the XR600R manual (same bolt size, same fork size), it has them

listed at 20ft.lb for the upper and 24ft.lb for the lower. Note that this

is for DRY threads. If you use these values with grease or oil on the

threads, you WILL overtorque or snap the bolt.

 

Q: What are the different camshafts available for the 400?

 

A: There are aftermarket manufacturers of camshafts and these come in

different grinds. Sometimes you see cams being marketed as a mid and

upper RPM power increase, or being all about upper RPM power increase,

while sacrificing some of the low RPM power. Given the 400's primary use

is as a trail bike nowadays, and that the XR motors have never been designed

as high-rev screamers, I'd say the full out top end, race designed cams

is not the right choice for most people. When choosing a camshaft, make

sure that the cam material is compatible with the cam followers. Some

welded type cams will wear out the softer stock followers, and need them

to be hardwelded/hardfaced for maximum life. The other thing to note is

that most aftermarket (non-Honda) cams don't have the automatic

decompressor and backfire decompressor features built in like the stocker.

 

As a general rule, cams with highest lift, longest duration and large

overlap (intake and exhaust open at the same time) are designed to produce

more top end power. The following chart, taken from the TRX400 users

group gives lift and duration. Unfortunately, the overlap (or equivalently,

lobe centres, or even angular location for .050 lift) are not given.

 

Lift (inches) Duration @ .050" lift

------------- ---------------------

 

IN EX IN EX

Stock TRX 0.316 0.302 234 238

 

Stock TRX* 0.327 0.321 236 234

Per Megacycle

 

Stock XR400 0.326 0.321 240 244

 

White Bros. All Around 0.345 0.335 240 248

 

White Bros Track 0.351 0.345 256 256

 

Honda HRC 0.351 0.339 254 256

 

WEB 450/451 All Around 0.351 0.345 256 256

stock springs

 

WEB 479 Track All Arnd 0.378 0.378 250 250

springs, guides, hardface

 

WEB 463/9I Race Only 0.385 0.371 272 270

springs, guides, hardface

 

Megacycle 196-X1* 0.346 0.346 246 246

Torque/ Mid-range

Must Hardface

 

Megacycle 196-X2* 0.378 0.378 254 254

Mid-Top end

Race Piston / Springs

Must Hardface

 

GT Thunder 0.351 0.345 256 256

 

[* Duration @ .040]

 

 

The following numbers for the stock XR400 cam are in the service manual.

At 1mm lift (valve or cam; or are rockers 1:1? Not sure, it doesnt say...)

 

Intake open 11 BTDC, close 41.5 ABDC - duration 11+180+41.5 = 232.5

 

Exhaust open 40 BBDC, close 10 ATDC - duration 40+180+10 = 230

 

Overlap: 11+10 = 21 degrees.

 

For comparison, 1mm is about 40 thousandths of an inch, so duration numbers

for the same cam but given at 50 thou would be slightly less (maybe 228 or

so?). Not sure what to make of the stock XR cam being listed as a 242-ish

duration in your list, when the manual says 232-ish (but the same manual

says the XR400 uses 19 gallons of fork oil per leg, so...)

 

In the cam chapter, they give the lobe heights as follows:

 

Intake: Standard 1.2175 -> 1.2215, wear limit 1.213

Exhaust: Standard 1.2137 -> 1.2176, wear limit 1.209

 

To convert these numbers to cam lift, you have to subtract the size of the

base circle, which isn't given. But if I cheat and use the above XR400 lift

numbers, then the intake base circle is 1.220-0.326 = 0.894" and exhaust is

1.216-0.321 = 0.895".

 

 

---------General de-restricting or Uncorking ------------

 

Q: What does it mean to "de-restrict" or "uncork" my new bike?

 

A: For Honda to be allowed to sell these bikes in various countries, they

must comply with regulations for sound output, emmissions, and maximum

power output. These are concerns that the original bike designers

didn't have to worry about until the bike design was finished.

To comply, Honda took the final design and then intentionally

made a few small changes to cripple the bike to a level that your

government has deemed acceptable. These changes included making the

final stage of the muffler with a small output size, setting the

carburettor up to use the absolute minimum amount of fuel, and partially

blocking off the air intake to the engine. The bikes in some countries

are more crippled than others. This is nothing new, even the 1st single

shock XR's from back in 1981 had muffler inserts and intake restrictors.

But starting in 1998, Honda made the restrictions harder to remove

so that they could also run even leaner carb jetting that would be

otherwise too lean for an unrestricted bike.

 

So, to de-restrict or uncork your bike means to undo all these small

changes that reduce the power output of your bike. You are aiming to

make it like what engineers originally intended, and not what the

regulations mandated. These types of regulations typically don't

apply to motorcycles used on a closed course, but bear in mind that

in doing these types of changes you may be technically breaking some

local and federal emissions regulations and laws if the bike is used

on public land.

 

 

Q: Can I de-restrict the intake and exhaust and not touch the carburettor

jets, or at least do that part later on once I get the jets?

 

A: No and no. The jets that are fitted to the carb are going to be

extremely lean once the restrictions are removed, since the motor can

now inhale and exhale a lot more air. Running lean will cause the motor

to run hotter than normal, and it will not have the power output that

it will have when properly jetted. Order the jets before you start.

 

 

Q: How do I de-restrict the airbox intake?

 

A: This depends on the year of your bike. The 1996 and 1997 bikes had a

two part intake duct into the airbox under the seat. A rubber part fit

into the square opening in the top of the airbox and a plastic restrictor

fit into this rubber part. To de-restrict the intake simply required

removing the plastic shove-in duct. This was the way the XR's were right

back to the very 1st single shock XR-R in 1981.

 

In 1998, Honda abandoned the two part intake duct in favour of a single

piece rubber unit that incorporated the function of both pieces of the

prior design. So, to allow unrestricted air flow into the airbox with the

newer bikes, most people just pull out the whole rubber thing and leave the

top airbox opening as is. Others who do a lot of water crossings like to

buy the old 96/97 rubber duct (part# 17240-KCY-670) and fit it into the

opening so that water that splashes on top of the airbox is directed away

and down the sides. You could do something in between by simply laying a

bead of black silicone around the top opening in the groove in the plastic

which would direct some surface water away, but note that a small amount of

water in the airbox is not a big issue, as it will just drain out the

bottom.

 

While you are working in the airbox area, note that the stock airbox drain

is a stiff plastic piece of junk that never really closes all that well.

If you are the type that likes your knee deep water crossings, then

Honda makes a nice flexible rubber one that you will find on the XR600R

and XR650R, (part number 17358-HM8-000).

 

 

Q: Are there any other intake restrictors?

 

A: Yes, on some bikes originally for Australia and shipped to some African

countries and "grey-market" imports found in the UK. On these "U" bikes,

there is a restrictor that is molded into the part that goes between the

carburettor and the cylinder head. According to the information I have,

the "U" (Australia) models had the restricted intake from 1996 to 2000

inclusive. The unrestricted part# is 16211-KCY-670, and the restricted

part# is 16211-KCY-650. People have indicated that the restriction is

molded into the bakelite like material but can be removed with care by

scraping with a sharp knife or using a rotary tool. In fact there is even

an instruction sheet from Honda that depicts the end user scraping the

obstruction out. If you have this intake restrictor, then you also have a

super small main jet that needs to be replaced too.

 

 

Q: Is the stock air filter also a significant intake restriction?

 

A: With its higher density foam and backfire screen, it will be more

restrictive than most aftermarket filters, but it isn't going to be a

crippling restriction. Keep in mind that the same filter was used in

the XR600R as well, with 50% more displacement than your bike has.

The stock foam on a modified cage (see below) is a nice setup and will

ensure your ride gets clean air in the worst conditions.

 

 

Q: What is all the steel screen in the stock air filter support cage for?

 

A: This is the backfire screen. It is supposed to be there to prevent an

engine backfire from getting to the the oily foam air filter and setting

it on fire (yes it can happen, I've heard it reported for the XR650R).

Most likely to happen after a crash where gasoline drools out of the carb

and wets the filter. That is why people hold the kill button while trying

to clear out a flooded bike with the decompressor after a crash.

 

 

Q: Can I remove the backfire screen from the stock cage?

 

A: Yes if you want to and are prepared to accept the small risk of having an

air cleaner fire (I've not seen one reported for a 400 or 250). The UNI

filter comes with a cage and it does not have a backfire screen. Only do

this if you like the fit of the stock cage better (as I do) or you can't

get aftermarket filters where you live.

 

If you try and cut the wire screen away, you will end up with a mess of

wire strands and will always be worrying if bits of wire are being fed to

your engine. So don't do this. The only way to do a decent job of it is

to gently heat the metal under the glue bonding the two parts together with

a small torch. If you don't heat it excessively, the metal anodizing will

even remain intact. Keep heating it until the glue just starts to flame,

and then move the torch slowly around the perimeter until all the glue has

flamed up. Once the glue has been sufficiently burned it will easily

scrape out and the two halves will fall apart allowing you to remove the

mesh assembly. You WILL HAVE TO DO THIS OUTSIDE in a breeze, as the burning

glue smells horrible and probably takes years off your life if inhaled.

Clean up the two parts you want to glue back together. Use a flat surface

to ensure the base ring is flat and undistorted before gluing. I used a

bead of Bulldog Grip PL Polyurethane adhesive around the base ring, since

the foam is also polyurethane. Wiggle the two parts to ensure the glue wets

well onto both surfaces and then place it back on your flat surface with

a small weight on top. Let cure for the recommended amount of time.

 

 

Q: What do you mean - the stock air filter cage has an air leak?

 

A: If you look at the centre post on the stock filter cage where the hold

down engages into, it is only tack welded onto the rest of the cage. It is

possible for dirty air to go down into this post and between the layers of

metal that make up the post base and the rest of the filter cage, thus

bypassing the filter. It isn't a huge gaping hole or anything, but it

doesn't hurt to wipe some glue down in the bottom of the post tube when you

have the PL polyurethane out already.

 

 

Q: Why does the UNI filter have this 1" wide foam stripe across the

opening when the Honda one doesn't?

 

A: UNI claims it is there to keep the sides together to ensure they are

clamped between the cage and the airbox flange. Of course they recommend

that you leave it there as well. Lots of people find it an unacceptable

hassle when removing and installing the cage into the foam - to the point

where it feels like you will rip the foam trying, and so they simply snip it

off. If you do this, then pay close attention when installing the filter

to ensure that the sides do get clamped in place. The Honda one uses a

leather (or vinyl) ring to keep the required shape of the filter base,

and doesn't rely on having the foam folded 90 degrees and pinched anywhere

around the base.

 

The 400 airbox is even smaller than the older airbox found on the 600 and

pre '96 XR 250's, making it it so hard to work in there. To make it worse,

the 400 airbox flange is part rubber (vs. the old steel) making it even

harder to tell when you have the filter properly seated. I find the Honda

cage and foam provides a more positive sense of feel when "in place" than

the UNI, and this is important to me with my big hands and inability to see

in there. Besides, I compared a backfire-less stock filter against the UNI

and couldn't notice any significant difference on an otherwise

de-restricted and rejetted 400. Maybe a dyno would have shown a small

difference, but I'm not racing for $$$$.

 

 

Q: What air filter will filter the best?

 

This is almost as religious a topic as recommending a motor oil, but

for what it is worth, I've had the chance to compare three different brands

of filter at the same time (K&N, UNI, and new OEM Honda). These style filters

fit essentially all the XR's except for the liquid cooled XR650R and date

back to the "KN5" XR350 of the early '80s.

 

Air filtering in a foam filter (as I understand it) relies on the fact

that the momentum of the dirt particles means that they want to travel

in a straight line. As the air dips and bobs through the foam, the dirt

should eventually plow into some oily foam and stick. However, as you go

to finer dirt, the momentum of a dirt particle is less and it has a better

chance of being steered through the filter along with the air stream.

 

Both the Honda and the UNI are two stage foam. The interesting thing is

that the "fine" foam on the UNI is about the same pore size as the coarse

outer foam on the Honda. If you hold the Honda filter up to the light,

you can't even see any illumination through it, let alone straight through

light. With the UNI, you get a yellow illumination from the yellow inner

foam, and if you look closely while moving it around, you will see a few

tiny rays of light make it straight through. This is for clean, non-oiled

filters. So which is better? I'd say it depends on your application and

that can be broken down into terrain and whether you race or ride

recreationally.

 

In eastern terrain, where you are probably filtering more wet

dirt, bugs, grass seeds, chunks of leaves, etc. and less fine fine dust,

the stock filter may tend to skin over, as the larger particles get trapped

very close to the surface while the rest of the filter remains relatively

clean. I think this is what UNI has targeted with the coarser outer foam

on their product, with the idea being that the larger particles are

dispersed through that layer instead of growing a restrictive layer over

the surface. But in dry dry dusty conditions, having the filter skin over

is probably less of an issue, and I'm thinking the higher foam density of

a stock filter will mean that there is more oily foam in the path of the

air and thus it will pick up a little more of the fine stuff than a UNI.

 

The second part of the application depends on why you ride your bike.

Are you a racer where maximum flow and minimum risk of plugging

is most important? Or are you just out to have fun, and thus maximum

filtration and maximum engine life are your top concerns?

 

No, I didn't forget the K&N. It is a totally different animal, more

like a paper car element in design. The air only has to pass through

a layer of cotton, and filtration depends largely on the size of the

weave of the cotton. Although as others have pointed out, I can't say

I'm in love with the quality control of the gaps in the cotton weave,

with some gaps appearing to let quite a bit of light through; much more

than the tiny amount you see through the UNI. It also doesn't hold

as much oil (obviously) - and I equate stored oil with the amount of fine

dust the filter can hold onto before becoming "dry". The other downside

is that on this K&N filter (XR250/XR400/XR600) you get a tin lid on

the filter front, instead of useful filtering area. In its defence,

I'd have to say that it is only 1/2 a filter when used alone - K&N

sells pre-filters or "filterchargers" as I think the marketing droids

have called them. I'd recommend using a pre-filter on a K&N and always

keep the assembly well oiled. There are independent tests that you can

find on the internet that show the cotton gauze type filters don't filter

out as much stuff as a foam filter until they get some dirt on them.

 

 

Q: How do I de-restrict the exhaust?

 

A: There are several options; which you choose will depend on your budget,

your fabricating skills, and how much exhaust noise is acceptable for your

riding areas. Buying an aftermarket pipe is self-explanatory.

If you are retaining the stock head pipes and muffler

assembly, then you are looking at modifying or replacing the stainless steel

part at the very back that is held in with three bolts. On the '96 and '97

bikes, there was a secondary insert that slides in the stainless part.

This secondary insert with the tiny hole could be removed, leaving a more

reasonable sized hole (1 3/8" or so). On the '98 and newer, the secondary

insert is welded into the stainless part, and so you are stuck with

the 3/4" output hole unless you modify or replace it. The following

questions and answers expand on each of these options.

 

 

Q: What was the "Gordon mod" for the '98 and up exhaust tip?

 

A: If you have the '98 and newer tip, the cheapest and easiest (but most

Red Green like) modification is the one originally suggested by Gordon.

He suggested drilling 3 to four holes slightly under 1/4" into the flat

surface between the 2" stainless outer ring and the 1 3/8" part that the

exhaust currently comes out of. These holes would be in an area so as to

leave the spark arrestor screen function intact (assuming you drill straight

in and don't waggle the drill all over.) By going slightly under 1/4" he

reasoned that he could plug the holes with 1/4x28 set screws if he wanted

to revert back to 100% stock. He calculated that three 1/4" holes would

increase flow area by 21% over what the stock 3/4" diameter output gives.

 

While this may sound good, keep in mind you are comparing it to the

size of the original heavily restricted outlet size. Even after the three

holes are added, the total area for flow is still less than the area

of a 7/8" dia. circle. Also note that a bunch of small holes that add

up to an area of "x" sq.in probably don't flow as well as one hole with

area "x", due to edge effects. I also have concerns that a small sharp

edged hole is more likely to generate poor flow and whistling/turbulence

noises. So if you do decide to do this, use a sharp bit with cutting oil,

drill slowly, don't force it through at the last bit, and use a round file

to try and remove the flash from the backside of the hole as much as

possible (without poking the spark arrestor screen).

 

 

Q: Can I use the 96/97 exhaust tip in my newer bike?

 

A: Yes, the pipe and where it bolts in with the three bolts is the same.

There are a lot of people who order the 96/97 exhaust tip to replace the

restrictive version found in newer bikes. It does not come with the slide

in restrictor that has the tiny 1/2" output, which is good since it is

probably of no use to anyone anyway.

 

 

Q: Can I quieten down the 96/97 exhaust tip somehow?

 

A: If you find the unrestricted 96/97 tip too loud, then yes, there

are a couple of aftermarket companies that make a slide in silencer

section that isn't as restrictive as the 98 and newer tip, but still

shaves off some noise. Vortip and Thumper Racing to name a couple.

Baja Designs sells both I think.

 

 

Q: Is there any other bolt in exhaust tips to choose from?

 

A: Yes, I think Ballards make a complete tip (i.e. whole chunk that goes in

with the three bolts) that uses a turn down to help reduce noise further.

Or if you have a bit of fabricator in you and a friend with a MIG welder,

you can craft one up of your own design. You need to use stainless mesh

like the Honda tip has for a spark arrestor if required in your riding

areas. A good starting point is to make one similar in design to the

silencer inserts found on late '80s and early '90s XRs but with a bigger

diameter for flow. Don't go bigger than a 1 3/8" flow ID of perforated

metal tube, or it will probably be too loud. About 5" of 2" to 2 1/4" OD

thinwall pipe can be used to hold packing material against 5" of perforated

flow tube. You will also need to make a flange with the three bolt holes

and a suitable washer shaped bit of metal to close up the other end by

joining the perforated pipe to the outer tube. Then weld it together.

Add a turndown on the outside to further decrease the noise factor.

 

Q: What other noise deadening stuff is inside the stock pipe?

 

A: There is about 2.5lbs of stuff inside the walls of the stock pipe.

Once the header pipe enters the tapered/cone section, it joins into

another pipe slightly larger in diameter than the headpipe. You can see

the other end of this pipe when you look in the back with the stainless

steel tip out. This additional pipe has a perforated section which is

wrapped with a loosely fitting powerbomb that has a thin layer of glass

packing that is protected from the perforations by another thin layer of

stainless steel wool. There is about a 1/2" hole in the pipe at the edge

of the powerbomb that allows pressure equalization into the tapered

chamber section of the pipe. A large disk seals this chamber to the

powerbomb pipe right where the tapered section is welded to the 4" muffler

tube. From there, the muffler tube is lined with a thin layer of glass

packing, then stainless wool, and finally the perforated metal that you can

see when the tip is out of the pipe. The packing on the muffler tube walls

does most of the noise deadening when you are using a free flowing exhaust

tip.

 

Be aware that in winter climates, or after short trip use, the muffler will

not get hot enough to drive out the condensation from the packing and the

muffler will rust from the inside out over time.

 

 

Q: What is this about grinding the welds in the stock exhaust headpipe?

 

A: If you unbolt the headpipe from the motor, you will see that the round

flanges that press against the copper sealing gaskets are pushed over and

then welded to the two pipes. The roundness of the weld bead protrudes

about 3/16" into the flow area at the entrance of the pipe all the way

around. This can be a slight flow restriction. If you are running a free

flowing aftermarket exhaust or a less restrictive exhaust tip, then you can

clean these welds up a bit. If you are running the stock exhaust tip (with

or without the Gordon holes) then it probably isn't worthwhile, since there

are bigger restrictions elsewhere.

 

What you want to do is flatten off (remove) the top rounded part of the

weld bead, but not take the weld right down to the diameter of the pipe, as

this could possibly weaken it and cause the pipe to crack away from the

flange. In other words, be happy with a 90% improvement and don't get

carried away. The best way to do this is to buy a carbide tipped cutter

from your local speed shop (like you would use for porting cast iron heads)

and put it in an air powered die grinder. The budget method will take a

lot longer, but if you are patient you can do it with some cheaper die

grinding stones fitted in a standard 3/8" drill.

 

 

Q: What is this giant crankcase breather thing on my California bike?

 

A: As part of the tighter emissions standards in California, the fumes

from the crankcase are fed into an oil separator and then fed back into the

airbox to be burned by the engine. On all the other bikes, the breather

from the crankcase under the carb goes a short way to a tee and one end of

the tee has a pipe dead end up under the seat, and the other end goes down

to underneath the engine with an airbox drain like tip on it. Legal issues

aside, if you convert a California bike to match those from other states,

then make sure you plug the original connection to the airbox boot, or it

will suck dirt and dust into your engine through that opening.

 

On the 49 state XR650, the crankcase vent goes directly to the fitting

on the airbox, and so that is another option you may want to consider.

 

----Carb Questions -----------

 

Q: What are the standard jet settings for my bike?

 

A: This depends on the year and country for which your bike was intended.

In this context, California is essentially a separate country that gets a

different bike from what the rest of the US gets. To start with, the 96/97

bikes shipped with a 162 main and a 62 pilot. This jetting was meant to be

used with an unrestricted bike, i.e. no intake restrictors, and the 96/97

exhaust tip without the insert. These early bikes came with the J6DF

needle (16012-KCY-670) and a #458 slide, but the recommended setup is to

switch to the A16A needle (16012-KCY-681) and #408 slide that is found in

the newer bikes, to obtain a smoother throttle response. Baja Designs offers

a service where they will mill off about 0.020" of your #458 slide to match

it to #408 slide specs. Note that when ordering a new needle, you get both

the needle jet and the jet needle. The needle jet goes above the main air

jet and the jet needle has the clip in the 3rd clip groove. If you see a

part number for the A16A that has "NKK" in it, that is just the HRC part

number that was used prior to it being a standard issue XR400 (i.e. KCY)

part.

 

In 1998, all bikes got the A16A needle and #408 slide, with the exception

of California, who got an A2EA needle. Standard jetting of North American

(49 state plus Canada) bikes was cut back to a 142 main and a 52 pilot,

with California getting a 138 main. The ED and U bikes got a 60 pilot for

98/99 and then a 55 after that. The ED bikes retained the 162 main jet

for all years, while the "U" bikes destined for Australia are an exception,

as they shipped with a puny #60 *MAIN* jet in conjunction with the intake

manifold restrictor that was unique to those models.

 

The listing I have shows that the 98 and up ED/U bikes have a different

main air jet (part number 16165-KCY-681) versus the 16165-KCY-670 found

in all 96/97 models. It shows the '670 being in the 98 and up North

American bikes, but John Rushworth has it listed as being a #100 (Keihin

size number) for the 96/97, and a #90 for all 1998 and newer. The main air

jet is the long stalk that the main jet screws into.

 

 

Q: What are the recommended jet settings for my unrestricted bike?

 

A: This depends on just how unrestricted it is, and of course the

altitude and temperature. The service manual and even John Rushworth's

collection of bits have the altitude correction tables, so all you need

to do is decide on a baseline for the sea level/room temperature jet sizes.

The 162/62 baseline is appropriate for a bike with intake restrictor

removed, aftermarket filter and aftermarket free flowing pipe, and is

what you will find recommended on FMF's site.

 

If your exhaust is not quite as free flowing as that, (e.g. stock 98+

tip with "Gordon Mod" holes in it) then you might want to go down a

bit. Gordon, in his original posting went with the 160/60 as was

recommended by Cycle News at the time. The Honda service manual lists

using a 158/60 combo in the 96/97 bikes when the exhaust insert is

fitted into the 96/97 stainless tip. (Again, these are for sea level,

and at room temperature - apply a correction factor for your area.)

 

 

Q: Why aren't there part numbers for all the possible jet sizes?

 

A: Both the main jets and the pilot jets always end in size numbers of

zero, two, five, or eight. Meaning that you can get a main jet that is

140, 142, 145, 148, 150, 152, 155, 158, 160, 162, 165, 168 and so on.

For the pilot or slow jet, the numbers will be 52, 55, 58, 60, 62 and

so on. The part number for a main jet is 99113-GHB-###0, where you

replace the ### with the size you want - e.g. 162 is 99113-GHB-1620.

Similarly for pilot jets, 99103-437-0##0 - e.g. 62 is 99103-437-0620.

 

 

Q: How do I translate those jet settings to the altitude where I ride?

 

A: As you go up in altitude, the air becomes less dense - meaning for each

gulp of air the engine takes in, there is less oxygen per gulp that can be

burned with the fuel. So, to keep the oxygen to fuel ratio constant at

the same ratio it would be at sea level, the jet sizes are reduced.

 

Using the aforementioned correction tables (graphs, actually), an

elevation of 2000m (6500ft) at room temperature (20C/70F) gives a

correction factor of 0.94, so if you chose a baseline of 160, then by

multiplying you get 160x0.94=150. You will have to round up or down

to the nearest existing main jet size.

 

 

Q: What about the pilot screw setting on the carb?

 

A: You can think of the externally adjustable pilot screw as a fine tuning

on the pilot jet that lives in the float bowl. Usually this is tuned to

give the highest idle speed once the bike is at operating temperature.

Don't turn the screw in hard against the stop or it will damage things.

The ideal operating range is approximately from 1 to 2 1/2 turns out.

If the best idle speed is obtained with the screw at less than one turn,

you can reduce the pilot jet size one. If the best idle speed is obtained

with the screw open more than 2 1/2 turns, then you can increase the pilot

jet one size. If the pilot circuit is too lean, the bike will be more

difficult to start when cold, and will require the choke for a longer

period of time.

 

Q: Do I need to remove the carb to change the jets?

 

A: For most people no. If you are only changing the main and pilot jets,

then this can be done from the bottom, by removing the float bowl while the

carb is still on the bike. If you are changing the needle clip setting or

the needle itself (as for California bikes) then you are better off taking

the carb off.

 

 

Q: Do I need to remove the subframe to get the carb out?

 

A: No. You can probably get it out without if you are willing to heavily

deform the airbox boot, but I think it is easier to just undo the three

intake manifold bolts and use that to bring the assembly out. Be careful

on reassembly to get the o-ring in the intake manifold properly in place

before re-installing the three bolts. If you are more comfortable with

removing the subframe than the intake boot, then you may want to remove the

lower bolts and pivot it upward on the top bolt after unclamping the

airboot from the carb. Use a motorcycle tie-down from the ceiling to hold

the subframe up out of your way.

 

Q: I've read that I should set the float height?

 

A: There are some improvements that can be made in this area, but it

depends on how and where you ride whether it will be worthwhile for you.

There are two aspects of setting the float height. The obvious one is the

height at which the floats have risen up enough to shut off fuel flow into

the carb bowl. The second, and not so obvious one is to set/limit how

much down travel the floats have. The service manual doesn't cover this

second one at all.

 

Okay, first the shutoff point. Usually this is set from the factory at

14.5mm as per the service manual instructions. I recall reading in

one magazine article where they noticed a significant improvement in fuel

economy when they lowered the 400 float height slightly. I wouldn't be

surprised, as I notice the ends of the carb vent lines regularly look to

be damp with fuel after anything but the smoothest terrain. But I haven't

got around to experimenting with that yet.

 

Now for the float hang or down travel. When holding the carb in its normal

operating orientation, you will see the metal tab on the floats which hits

the carb body and limits how far down the floats can go. The generally

agreed upon setting for this is 19mm, with the factory setting being

several millimeters more. You will see some people argue that this doesn't

matter, since the float can't "sink" but that is the wrong way to look at

it. In a "g-out" or over rough terrain, the downward momentum of the float

can push it into the fuel and give a temporary rich condition (a stumble).

You will also notice an improvement if you ride balance point wheelies

(i.e. where engine revs are constant). I found it would quickly start to

load up and miss/stumble from excess fuel. I limited the down travel on

the floats *without* making any changes to the float height, and this alone

made it so I could ride smooth 4th gear wheelies to beyond when the front

tire stopped spinning.

 

---- Maintenance Issues -------------

 

Q: How do I check the oil?

 

A: Checking the oil is supposed to be done after the bike is fully warmed

up and allowed to idle for a bit. The reading is supposed to be taken just

after shutting the bike off and with the dipstick just lowered in and not

threaded in. Doing a few circles around your truck to use the transmission

tends to help get more consistent readings. Others get into the habit of

checking the oil after returning from a ride (be sure to clean dirt and mud

away from around the dipstick!).

 

 

Some people have trouble getting consistent oil readings, and it helps to

understand how the oiling system works. There are essentially two oil

pumps on your bike. One is responsible for taking oil from the tank in the

main frame tube where the dipstick is and pumping it around to all the

bearings and pivots, where it then runs down by gravity and pools at the

bottom of the motor. The second pump is the return pump, and it takes the

oil from the bottom of the motor and returns it to the oil tank in the

frame. For this to work, the return pump is designed to pump slightly more

than the lubrication pump, so that it doesn't fall behind and starve the

lubrication pump. Pumping rates can be influenced by the oil

temperature as well, which is why more consistent readings are obtained on

a warm bike.

 

Now, if your bike sits for many days, some of the oil will eventually flow

down from the frame tank and into the motor. If you check the oil at this

point, the dipstick will read low or even empty, and if you add oil, you

will end up over filling it. When you allow the bike to idle for a

minute while held vertical, it will help allow the level to stabilize. When

on the sidestand, the oil runs away from the lower pickup, and so you will

end up with more oil in the motor and less in the frame tank, thus giving

you a lower reading.

 

Q: What if I've overfilled the oil?

 

A: If you have overfilled the oil, chances are excess oil will be forced

out the crankcase breather tube, which is the big black vent line under the

carb. On most bikes it just ends under the seat, but on California bikes,

it eventually ends up in the airbox. If you have oil in the breather tube,

the crankcase pressure can't vent properly, and this is harder on the

engine seals like the one behind the front sprocket. There is an oil level

check bolt on the side of the engine that can be used to drain some of the

excess oil once it has run down from the frame tank into the engine.

 

Q: What is this I hear about taking a new bike apart and greasing all the

pivots before even riding it?

 

A: Most of the bearings and pivot points on your new bike only have a

minimum thin film of grease wiped over the wear surfaces. The amount

of grease found on bearings looks to be about the same as the skimpy

amount you would find placed on a new bearing just to protect it from

rust during shipping. If you take it apart and make sure these pivot

areas are full of grease, then there is no air pockets for water to

seep in and start to rust things. Dry bearings that fall victim to

water contamination quickly rust and then grind themselves into a brown

black powder. This seems to be the most common bearing failure

reported. When you grease up a new bike, you can just add more grease to

what is already there. You don't have to worry about cleaning out all the

old crusty grease, or worry about grit and contaminants falling into parts

you are working on.

 

Q: What are the things I want to grease up?

 

A: You want to remove the shock and suspension linkage and the swingarm.

Most of these pivot points have a hardened steel sleeve that will push

out and reveal the needle bearings. A thin film of grease on the bolts

themselves will stop them from corroding inside the sleeves. Make sure

the swingarm bolt is well greased where it slides through the motor as

they seize here on neglected bikes. The front and rear axle bolts can use

a film of grease to prevent them from turning white with corrosion too.

You also want to remove the rear brake pedal pivot and pack that area full

of grease too. Remove the spark plug while the engine is still clean

and put a bit of anti-seize compound on the plug threads, since it will

probably be in there a while. Finally the steering head bearings can use

some more grease than the factory puts in as well. You really don't want

to fill the whole steering head with grease, as it will just puss out the

bottom from the heat of the hot oil circulating nearby and make a mess.

If you still have time to kill, and intend on keeping the bike for some

years, you can remove the other motor mount bolts one at a time and wipe

a film of grease on them too. Anywhere that an unprotected metal bolt

is in contact with aluminum will grow corrosion when repeatedly wet.

 

 

Q: How come I can't get the lower steering head bearing off to grease it?

 

A: It is a press fit over the steering head stem, and you don't want to remove

it unless you are going to replace the bearing with another one. Just take

your time and work the grease in between the rollers and the cage until

you are convinced there are no more air pockets left.

 

 

Q: Didn't some pro rider say that just a thin wipe of grease on the

steering head bearings was enough?

 

A: Yes, it was **** Burleson. He argued that you don't need to pack it

full like you would a wheel bearing, since it isn't turning very fast or

very much. But most of us "Joe Average"" types contend that it is better

to pack the bearings full of grease just like you would a wheel bearing

and put a generous layer over the races. This will minimize the chance

of water and rust damage to the bearings, as 99% of the people who have

had to replace them have found the old ones to be pitted and rusting.

 

 

Q: Are the seals for the rear brake pedal pivot in backwards on my bike?

 

A: Possibly. They are single lip seals, and on a new bike I found them

with the lip facing inwards. Meaning that if they are under pressure from

water (either from being sprayed or being submerged) the water pressure will

force past the seal and into the pivot. This also makes them hard to install

once you have filled the pivot area with grease. But with the lip facing

outwards, excess grease is free too ooze past the seal during installation,

and water pressure is not going to be able to force the seal lip off the

pivot shaft. (The service manual doesn't detail which way Honda intended.)

 

Q: Do I need to remove the subframe to get the shock and swingarm out?

 

A: No. Even though the service manual directs you to take the subframe off

to get to the shock, you can do it with only the seat off. Of course the

bike needs to be supported under the engine on a stand! If you want more

room in there, you can always undo the bottom subframe bolts and let it

hinge upwards on the loosened upper bolt and tie it off to the ceiling.

 

 

Q: What grease should I use?

 

A: Generally a quality grease that is listed as water proof and not just

water resistant. Apparently the aluminum based greases are more water

proof than the lithium based greases. Some people have found marine shops

to be a good place to buy highly waterproof grease. The grease should also

be listed as being appropriate for the type of bearing(s) that you are

using it on. Suspension pivot bearings are of the needle type and the

steering head bearings are the conical design like seen in conventional

automotive wheel bearings.

 

Q: Why aren't there any grease gun fittings like older XRs had?

 

A: Having grease fittings on the suspension fittings sounds like a good

idea, but the problem is that the grease never goes where it is needed

most. What happens is that once some of the old grease goes a bit dry and

cakes up, it blocks the grease flow, and so when you pump more in, it just

goes out somewhere else where the grease is still fluid enough to move.

Unless you stay on top of it and pump a squirt or two in at regular

intervals, you will find that the grease eventually only comes out one of

the two sides of the pivot, and so you'd have to take it apart to remove

the caked up grease anyway.

 

 

Q: What is the 1st thing to seize on a bike that hasn't been greased?

 

A: By far this is the big swingarm bolt that joins the swingarm to the

frame and also passes through the back of the motor. It only takes a

trace of water to creep in there, and a dry bolt will fester up with

corrosion in a short time. The archives of the discussion groups are

littered with horror stories of people who have spent countless hours

trying to get this bolt out, only to be reduced to a sobbing mess.

Don't be one of them.

 

 

Q: I'm a victim of the seized swingarm bolt - what do I do?

 

A: If you aren't in a desparate hurry to get it apart, then get a good quality

penetrating oil (people have said good things about PB Blaster) and apply a

daily spray at the frame/swingarm and motor/swingarm contact points when

the nut is loose. Each day try and rotate the bolt by the head back and

forth. Even if it only moves a micro amount, it will help break up the

corrosion and let the oil in. In extreme cases, people have eventually

resorted to hammering out the bolt. If you are going to do this, then use

something like a 1" diameter brass punch to hammer on, and support the

frame on the other side with something the bolt can pass inside of, such

as a length of pipe over the bolt head and up against an immovable object.

Don't use a small tapered punch. If you do use a small

punch that wedges inside the hollow bolt, it will spread the bolt, making

it too wide to go through the swingarm and motor. If you hammer directly

on the bolt, the threaded end will mushroom out and it again will be too

big to pass through. Some people have reported that a pneumatic hammer

worked well for them, but again be careful to not mushroom the bolt!

In the most extreme case, I have read of people who have had to

saw through the bolt so that the motor could be taken out of the frame

and then the remaining bolt bits were drilled out of the motor!

 

 

 

Q: Why shouldn't I take the spark plug out before cleaning the bike?

 

A: Have a look at where the plug is. You need a mirror to see down to the

base of the plug! And when you look down there with the spark plug boot

removed from the plug, you will see that it is a big dirt trap. After any

riding at all, dirt and small stones like to accumulate around the base

of the spark plug just waiting to fall into the motor once you unscrew the

plug. A pressure washer or compressed air is the best way to clean out the

area. Sometimes they wedge in there and won't blow out until you crack the

plug loose a turn or so. I've heard of people who carry a small length of

hose in their trail tool kit so that they can try to blow the area clean if

a trailside drowning warrants plug removal. Another option would be to lay

the bike down on such an angle that crud wouldn't want to fall down the hole.

(Turn the gas off 1st).

 

 

Q: How long should my spark plug last?

 

A: Unlike two strokes, your spark plug will last a very long time under

normal operating conditions. It is not uncommon for people to have gone

15,000km on the original spark plug! It doesn't hurt to pull it out and

inspect it as part of regular maintenance though. Some anti-seize compound

on the threads is a good idea, and do not over tighten it. Factory spec is

only 13 ft.lbs. The factory Honda plug socket is one of the few tools

thin enough to get down in there and onto the plug. If buying the Honda

socket, note that the price of the whole little tool pouch is usually a lot

cheaper than just buying the socket and the multi-wrench separately.

 

 

Q: Should I clean and/or filter my crankcase breather pipe?

 

A: On non California bikes, there is a short section of tube from the

engine that goes to a tee - a hose from the bottom of the tee goes down

just below the swingarm and terminates with an end very similar to the

one on your airbox drain. The top of the tee has a hose that goes up to

the subframe tube where the seat rests, and the hose is shaped so the open

end points downward.

 

The movement of the piston in the motor causes a pulsing, reversing flow

of air from the crankcase. With the top end of the hose open to the

elements, dust and dirt enter the top tube during the suck cycle and some

sticks along the oily inside wall of the tube. The bottom is sucked closed

and so essentially nothing comes in there. During the blow cycle, air

goes out the bottom (as well as out the top) resulting in a net flow of

air in the top and out the bottom. If you take the vent stack

off for cleaning on an average bike, you will find a lot of grunge in the

pipe at the open end, and the continual suck-blow pulses have migrated some

towards the tee and eventually trace amounts can get to the motor. The

drain on the bottom of the vent stack tends to go hard from continual

contact with oil as well.

 

So the idea of a filtered vent tube is sensible - you use a single large

diameter hose to a highly place _free_flowing_ filter to let the crankcase

pulses vent in and out while keeping the dirt and grunge out. The choice

of filter probably depends on what is readily available in your local auto

stores. Some of the filter manufacturers like UNI and K&N also offer

crankcase breather filters I think.

 

 

Q: What motor oil should I use in my bike? Synthetic? Conventional?

 

A: This question is one that is sure to start an opinionated controversy

no matter where or when it is asked. The discussion forums are filled with

pages and pages of crap written on motor oil, and you could read it from

now until you are old and grey. Advice that everyone will agree with is

to not be cheap and go too long between oil changes. Oil is the life blood

of your engine.

 

One of the advantages of synthetic oil is that it can

handle higher temperatures without degrading as badly as conventional oil.

This can be important on an air cooled engine as the cylinder head gets

quite hot, and you want your cam, rockers and valve guides to last as long

as possible. As an example, finding a good used cylinder head for the early

RFVC XR motors from around 1985 that didn't have an oil cooler is pretty

much impossible.

 

Don't use an oil that is listed as "Energy Conserving" in the

circular API symbol on the bottle - these have friction modifiers that are

to make the oil extra slippery for maximum fuel economy in car engines.

Since on your bike the clutch is in the motor oil, and it relies on

friction between a bunch of discs to transmit power from the crankshaft

to the transmission, some of these friction modifier additives can cause

the clutch to slip.

 

Follow the factory viscosity guidelines - that means running a 20w50 if

your riding is in a warmer climate, and 10w40 if you are riding in weather

below freezing. Components in the hot cylinder head have metal surfaces that

rub across each other under high pressure (cam lobes, etc). This sliding

action puts more demands on the oil than the typical rolling action you have

in a conventional ball bearing. If you use cheap no-name 10w30 from the

local bargain mall, this is where it will let you down first and you will

be looking at a noisy clattering engine requiring an expensive top end.

 

Synthetic oil that does not contain friction modifiers is generally fine

and they will not cause your clutch to slip. People have been using Mobil1

RedCap 15w50 in the big torque XR650R without any problems being reported.

Note that the lower viscosity grades of Mobil1 auto synthetic have friction

modifiers and are NOT recommended. There is also the motorcycle specific

Mobil1 synthetic aimed at the V-twin market that you can buy if that will

help you sleep at night. Also note that the factory viscosity

guidelines are for conventional oils - synthetic oils typically cover a

wider viscosity range.

 

Q: How about car oil versus motorcycle specific oil?

 

A: What, haven't you had enough yet?!? Ok. Again a two sided coin, and

you will have to decide who you believe. Some feel that the motorcycle

oils are overpriced when a quality car oil without friction modifiers is

up to the task. There are some test papers on the internet that support

this claim. Others argue these tests are are too old to be relevant and

feel that the motorcycle specific oils have a better additive package

since they aren't restricted to having only catalytic converter safe

additives. (Note that most street bikes are going to have catalytic

converters in the near future, so...)

 

 

Q: What will I find in the frame downtube oil screen?

 

A: Probably not much. On a new bike, you will find a few bits of gasket

and small metal chips that circulated out during the break in. After that

you will find even less, unless you cook a clutch or suffered internal

engine breakage that spit fragments all through your engine. There is also

a screen under the right hand sidecover of the engine that stops big chunks

from entering the part of the oil pump that moves oil from the bottom of

the motor to the frame tank.

 

-------- Engine Questions -----------

 

Q: Is there an automatic decompressor and how does it work?

 

Yes there is actually two. They both are part of the camshaft.

One works when the engine is turning at slow speed (below 800RPM)

to lift the exhaust valve and bleed off compression making it easier to

turn over. The second is a reverse decompressor - it engages via a one-way

clutch mechanism so that if the engine kicks back and tries to turn

reverse, it bleeds off the pressure so the kick start doesn't try to propel

your knee up into the handlebars and cripple you. Note that nearly all

the replacement or aftermarket cams do not have any decompressor mechanisms

on the camshaft.

 

Q: Can and should I remove the manual decompressor?

 

A: Sure you can, but whether or not you should depends on several things.

Firstly, the manual decompressor is used by a lot of people to clear the

excess fuel out of a flooded bike after falling down on the trail. They

pull the decompressor lever, hold the kill button in and the throttle wide

open, and kick it over several times. If you fall down a lot, you probably

don't want to be without it. Others use it as a regular part of their

starting ritual. Most of the aftermarket camshafts do not have any of the

factory Honda decompressor mechanisms described above, so the manual

decompressor lever is used to allow the kickstarter to be moved past top

dead centre without requiring excessive force.

 

If you do decide to remove the lever and cable, I'd suggest taking note of

the lever position on the cylinder head, and then making a small bracket

out of some stainless sheet metal that uses the nearby bolt to support the

lever in that position. Without it, the lever sags down until the return

spring has no tension on it and it will jingle about.

 

 

 

--------- Chassis and Suspension Questions ----------

 

con't

[spenx75]

Continue. . .

  Quote

--------- Chassis and Suspension Questions ----------

 

 

Q: What are the stock fork spring rates?

 

A: The stock springs aren't marked, but it is generally quoted that the 96

and 97 came with 0.38kg/mm and the newer versions have 0.40kg/mm.

 

Q: Who makes aftermarket fork springs and in what rates?

 

A: John Borg on one of the Yahoo groups made this nice summary:

 

Stock for 1996 & 1997

- 35mm OD x 510.4mm Long

 

Stock for 1998 & later XR400R

- 35mm OD x 536mm Long

 

Racetech Springs

- FRSP 3647

- 35.8mm OD x 472mm Long, these are 64mm (2.52") shorter

than stock 1998 or later, and have about 11.1" travel

before coil bound!

 

Eibach Fork Springs

- 984 Series is 34.9mm OD x 532 mm Long

- Available from Racetech for $80 in;

- 0.45 kg.mm, FESP 984045

- 0.47 kg.mm, FESP 984047

 

- 996 Series is 36.7mm OD x 510mm Long

- White Brothers lists this spring for an XR400

 

"So if you've got a 1998 or later, the Eibach Series 984 springs

work great, and you only need an extra washer or 2 to get stock

preload (rather than cutting spacers). But these springs are

too long for 1996-97 models, unless you want a whole lot of

preload.

 

I've been running the Eibach Series 984's in my 2001 XR400R and

they work fine. Had the Racetech, but didn't like the idea of

being so close to coil binding (when the coils all are touching

and the spring becomes a column)"

 

Thanks John!

 

 

Q: What is this about a simple do-it-yourself fork revalve?

 

A: For those that think the compression damping is too much, there have

been people who have removed the compression bolt assembly from the bottom

of the fork and removed the staked nut to reduce the stock number of shims

from 12 down to about five or six. Any of the XR400 discussion forums will

have more details on the removal process.

 

Q: What does adding preload spacers on top of my fork springs do?

 

A: Adding preload spacers on top of the fork springs does NOT change

the spring rate. What it does is simply change the static ride height.

Adding preload gives a very similar result to what happens when you

lower the fork tubes down in the clamps - it raises the front of the

bike up. So what does raising the front of the bike do, you ask? Well, it

causes a change in the rake and increases stability at speed in loose

terrain. Lowering the front makes for quicker turning if you weave between

handlebar spaced trees all day and never get above 30MPH.

 

For my tastes, riding style and typical terrain, I like the forks

down so the caps are flush with the clamps and an 11 or 12mm preload spacer

in each leg. The stock spring length worked out to give essentially zero

preload (fork cap just touches spring when forks topped out), so a 12mm

spacer gives 12mm preload on this bike. I find this works good on open

trails and dual sporting on loose gravel roads. I used a section of thick

wall aluminum tubing and had a friend part off chunks on a lathe to get

square cuts of equal length. Light and strong. Others have simply hacksawed

off chunks of ABS or PVC pipe or whatever was convenient. Appropriate

washers can be used to fine tune your preload setting if desired.

 

Running too much preload and/or not enough rebound damping can allow the

forks to top out when lofting the front wheel over logs and such. Click in

more rebound damping, or run less preload if this affects you.

 

Q: The rebound adjusters on my fork caps don't have the right click count?

 

A: The rebound adjuster is a needle valve in the fork cap, and it seats

into the damping rod that screws into the bottom of the fork cap. The

number of clicks the valve has depends on how far down you screw the cap

before locking it into place with the lock nut. The way to get this right

is to spin the clicker in to the maximum number of clicks you want to have

(13 or 14) and then gently spin the fork cap onto the damping rod until you

feel it stop. This is when the needle contacts the damping rod. Spin the

locknut up against the bottom of the fork cap finger tight, then back the

clicker needle out a turn or two so that it won't get any excess seat load

and then tighten the locknut to specs.

 

Q: What about setting rear suspension sag?

 

A: There are many sites on the internet that detail how to set/measure

the rear sag. In a nutshell, you are comparing the topped out (on a stand)

height from the rear axle to the fender to the same measurement with you on

the bike in a normal riding position. Numbers generally range from 95mm to

105mm, and I find I like it biased closer to the 105mm range as on the 400

chassis that helps with stability at speed.

 

Q: What about revalving the rear shock?

 

A: This is a loaded question. It depends on what kind of riding you do,

and what your thoughts on the current rear suspension action are.

It also happens to depend on what year of bike you have as well.

The 96/97 shock had a lot more compression damping and slightly more

rebound damping as well. I'm thinking it would have had to ride like

a tank on trails. Maybe they were thinking of SX/Moto valving then?

 

It is always hard to pin point what part of the suspension isn't doing

what you'd like it to. For me, I find the 98+ stock shock harsh and believe

that it has too much low speed rebound and a bit too much high speed

compression. This is from an eastern style trail use point of view,

meaning that I want it to work good over rocks, roots and rough trails, and

am not concerned with riding jumps at the track or doing big drop offs.

So I tried to reduce damping in those areas. (180lb on stock spring).

 

Doing the revalve yourself is not a job to be taken lightly. You are

dealing with an expensive part of the bike and there are lots of ways

to screw it up if you aren't mechanically inclined and don't have an

eye for attention to detail. You also need to have an idea how the

concept of how the shock works - i.e. how the different stages of

flat spring washers (shims) control the oil flow by restricting the

flow through the shock piston. Even then you have to allow for going

back in to the shock at least a second time since you probably won't

magically get or guess on the valving that gives the desired ride you

want on the first try since the combinations of shim thickness, diameter

and stacking orders are endless. Myself included - on my 1st try I went

too far with my reductions, but it provided a useful reference on what sort

of magnitude caused by that shim change, and thus I was able to make a

more refined decision on what to try next.

 

Maybe someday I'll outline some hints and tips here, but in the meantime

I will at least list the different valving for each year, and the valving

that I used. Again keep in mind that the desired valving is a very

personal thing, and what I like, you may think sucks swamp water.

 

 

*** XR 400 Showa Shock -- Rebound valving (Meaurements in mm) ***

 

 

1996/1997 XR400 1998 and up XR400 Paul XR400

Dia. Thick. Dia. Thick Dia. Thick

-------------------------------------------------------------------

34 0.25 34 0.20 -

34 0.20 34 0.20 -

34 0.20 34 0.20 -

34 0.20 34 0.20 -

34 0.20 34 0.20 -

34 0.20 34 0.20 -

34 0.20 34 0.20 -

34 0.20 34 0.20 34 0.20

34 0.20 34 0.20 34 0.20

34 0.20 34 0.20 34 0.20

34 0.20 34 0.20 34 0.20

34 0.20 34 0.20 34 0.20

34 0.20 34 0.20 34 0.20

34 0.20 34 0.20 34 0.20

34 0.20 34 0.20 34 0.20

29 0.10 24 0.10 24 0.10

...................................................................

34 0.30 34 0.20 34 0.25

33 0.30 33 0.25 33 0.25

32 0.30 32 0.30 32 0.30

31 0.30 - -

30 0.30 30 0.30 30 0.30

29 0.30 - -

28 0.30 28 0.30 28 0.30

26 0.30 26 0.30 26 0.30

24 0.30 24 0.30 24 0.30

22 0.30 - 22 0.30

22 0.30 21 0.30 21 0.30

 

Note that the 29x0.30 is listed as present in the 98+ bikes according to

suspensionnetwork.com but it was not present in the 2003 shock I worked on.

Also, additional 21x0.30 are used to adjust stack height to allow the

nut to clamp before running out of threads.

 

 

*** XR Showa Shock -- Compression valving (Measurements are in mm) ***

 

1996/1997 XR400 1998 and up XR400 Paul XR400

Dia. Thick. Dia. Thick Dia. Thick

-------------------------------------------------------------------

38 0.20 - -

38 0.20 - -

38 0.15 - -

38 0.15 - -

38 0.15 - -

38 0.15 - -

38 0.15 - -

38 0.15 - -

38 0.15 - -

38 0.15 - -

38 0.15 -

38 0.15 38 0.15 38 0.15

38 0.15 38 0.15 38 0.15

38 0.15 38 0.15 38 0.15

38 0.15 38 0.15 38 0.15

38 0.15 38 0.15 38 0.15

38 0.15 38 0.15 38 0.15

28 0.10 28 0.10 28 0.10

24 0.10 24 0.10 24 0.10

....................................................................

- 38 0.20 -

38 0.30 38 0.20 -

36 0.30 36 0.25 36 0.25

34 0.30 34 0.30 34 0.25

32 0.30 32 0.30 32 0.30

30 0.30 30 0.30 30 0.30

28 0.30 28 0.30 28 0.30

26 0.30 26 0.30 26 0.30

24 0.30 24 0.30 24 0.30

22 0.30 22 0.30 -

- 21 0.30 21 0.30

20 0.30 - -

18 0.30 - -

18 0.30 - -

 

 

Note that additional 21x0.30 are used on top of the compression plate

to adjust the piston height so that the rebound bleed hole in the

damper shaft remains centred in the middle of the piston (important!).

 

My valving used or removed existing shims with the exception of two

34x0.25 shims that I had left over from revalving another XR.

Some extra 21x0.30 to make up for the removed shims is nice to have.

 

I found my valving kept the tire on the ground better on trails, resulting

in better ride quality and control, and even then it still handled

high speed (60MPH) rough open sections somewhat whooped out by 4 wheelers

with less effort required than stock. Instead of having the

rebound clicker wide open all the time, with no range of adjustment,

I found myself running it around 8 clicks out, and going down to 5

clicks out was significantly more damped for those who like that

tighter feel.

 

 

Q: How can I make my bike feel like a more modern MX bike?

 

A: Yes, some people find the older style ergonomics with the big rise

at the junction between the seat and the tank is a bit dated. There

is a company out there called "A-loop" who sells a seat, tank, and tank

shroud package that will give your XR400 a more modern look and feel.

Common complaints about the package are the increase in seat height

and the slightly lower gas tank capacity.

 

-------- Electrical Questions -----------

 

Q: Why is my headlight brightness seem so miserable?

 

A: The stock headlight is only a miserable 35 watt incandescent

(non-halogen) bulb in a plastic lens. You can limp home in the dark

at a slow speed if you are caught in a bind. Going to a 55 watt in a glass

lens is an absolute requirement if you want to do any night riding.

For off-roading, there is an OEM glass lens that takes a 55W H3 bulb

and it fits right into the stock plastic. This lens first appeared on

XR500's in the early/mid 1980's.

 

 

Q: Can I really make my bike generate more electrical power to run a better

headlight?

 

A: Yes, and it is pretty much a requirement if you want to run anything

more than a 35 watt bulb. You can run the 55W H3 on the stock stator, but

it will be dim at idle. Your choices are to buy a new/rewound stator from

someone like Baja Designs or Ricky Stator, or rewind one yourself. Doing

it yourself is a tedious job, and if you aren't someone with patience, then

buying one is money well spent. If you do wind it yourself, there is

information on the internet to help you. The best setup for most people

is using three layers deep of #18 wire over all 10 lighting poles. It is

the easiest solution to wind, and will give approximately 330 turns total

and will provide about 100 watts at idle and 125 watts when revved up some.

 

 

Q: How can I add a brake light to my North American spec bike?

 

A: The Euro/UK/SA/Aus versions of these XRs have a functional brake light

in the same lens/socket as you have on your North American XR. The

lens even has the little E4 approval on it. But your bike lacks the

switch and the wires to run it. You just get the 5W tail light, even

though you still have a 5W/20W bulb inside there, since you aren't

originally supposed to use your XR on the road over here.

 

The wiring method I describe here might seem strange to some but the

reason for doing it this way is twofold: 1) you don't hack into your

original wires in any way, and 2) you use the switch to toggle

a ground and not a live wire, so in a switch failure or wiring

damage from a crash, the worst that can happen is your brake light

comes on, rather than shorting your whole stator to ground!

 

This assumes you get one of the hydraulic switches like the

Baja Designs one that has about 3" of wire leads and male terminals

already installed. Others (maybe XRs Only and Dennis Kirk?) also

sell similar switches, and sometimes you can get them with longer

wires. If your switch has longer wires, you are free to move your

plugs that will join to it up further out of the water and muck.

 

The stock 2 filament bulb has a 5W taillight and 20W brake light.

With the lame output of the stock stator, applying brakes at idle

will probably just dim the headlight and marginally increase the

brightness observed from the rear. A stator rewind is the real

cure for this and allows you to run a real headlight - which is an

absolute requirement for serious night use or dual-sporting.

 

Required:

 

- about 8' of #18 or #20 insulated wire

- about 2' of 1/4" thin wall PVC sheath to protect wires

- soldering iron and solder

- cheap-o multimeter or ohm meter (optional)

- two wire hydraulic banjo bolt brake switch

- recommended brake fluid (DOT4 usually)

- 1' or so of small clear poly tube that fits on brake bleeder

- two OEM style insulated crimp on terminals (to match/mate with brake switch)

- round crimp/solder-on lug to fit 6mm dia. bolt

- appropriate wire terminal crimper tool

- several wire/cable ties

- WD-40 or similar

- dielectric/silicone grease

- appropriate wrenches, screwdrivers, etc.

- a couple hours, some common sense and patience. (Not available in stores)

 

General Steps:

 

- remove old banjo bolt and replace with switch/bolt assembly,

noting placement of and re-using original sealing washers.

See manual for torque setting if unsure how much to tighten.

 

- wash away any spilt brake fluid with lots of water as soon

as possible so it doesn't eat your paint.

 

- attach clear hose to bleeder screw on caliper, forming a loop

or loose knot in the clear hose so that some fluid will stay in

the line. Loosen bleeder and slowly bleed the air from the rear

brake line until there is no sign of air bubbles. On some systems

you may need to re-close the bleeder each pump, prior to releasing

the pedal, so that it draws from the reservoir. Do not let the

external reservoir run dry while pumping out all the air bubbles;

top it up as required. (If unsure about doing this step, see a manual

for more details, or take it to someone who knows what to do.)

 

- fully tighten bleeder, remove clear hose and again clean any spills.

It doesn't hurt to absorb fluid out of inside of bleeder prior to

replacing rubber cap, so it is dry and won't be corroded over time.

Check that rear brakes are actually working as they used to.

 

- use multimeter on low resistance setting (usually "Rx1", or 200 ohm

or less) and check across leads of switch shows 0 -> 1 ohm when brake

pedal is depressed, and infinite resistance (>200 ohm) when pedal

is released.

 

- remove seat

 

- measure off enough wire to go from inside tail light along original

wires to plug and across frame, down alongside brake reservoir hose

and to the leads on the switch. Leave enough slack in the subframe

front bolt area so you can pivot subframe up into the air for shock

maintenance without wire stretching/breaking.

 

- remove taillight lens and 3 6mm bolts holding in socket assembly.

 

- unplug taillight from bike harness and remove socket/wire assembly

from bike, paying attention to wire routing, and colours of wires on

both sides of the plug as you will be inverting these.

 

- use a small (watchmaker/glasses repair) screwdriver to depress the tiny

lock tab on the blades inside the taillight plug while someone else

gently pulls on the wires to free them from the plastic housing of the

plug. Note the lock tab orientation with respect to the plastic.

 

- ensure the lock tab is slightly elevated on each blade and re-insert

them opposite to where they were, so that blue plugs into green and

vice versa when you go to reinstall it. Your colours may be different,

as some used a brown. This step is what allows you to switch ground

and not a hot wire, in case you were wondering...

 

- remove bulb and unscrew the socket assembly from plastic base, then

pop the rubber feed-thru/grommet from the plastic (use wd-40 if desired)

 

- use a small drill (less than 1/8") to make a hole in the rubber feed-thru

close to the other 2 wires. Do not damage the other wires with the

drill as it goes through! Do not drill so close to the edge as to

expose the new wire through the side of the grommet where the plastic

will then rub on it!

 

- untape the black outer jacket near plug and feed the new wire along the

other two (you may find it easier to feed a stiff wire from the other

end first and then pull the final wire through, and use wd-40/lube)

 

- feed wire thru new grommet hole (again use lube as required)

 

- strip off 1/8" of wire insulation and lightly tin wire end with

a small amount of solder to fix strands from fraying

 

- feed the end of the new wire into empty socket hole until

tinned wire end is just flush with the top of the unused/empty

metal contact inside the socket.

 

- solder the tinned wire to the metal contact, using just enough

solder to match the height of the other original contact.

 

- retape sleeve around all three wires and reinstall taillight

assembly (a small amount of dielectric grease on the bulb

contacts isn't a bad idea) and re-route wires as they were.

 

- plug in tail light wires to bike harness, ensuring that

the wires are now swapped over as compared to what you

wrote down when you unplugged it.

 

- route the free end of the new wire down toward the switch

in a similar fashion to as when you measured its length.

 

- measure off a 2nd bit of wire to run from new switch lead

along the 1st new wire (up brake reservoir tube) and to 6mm

bolt on top of airbox

 

- measure off a bit of protective PVC sheathing slightly shorter

than this new 2nd wire wire

 

- slide PVC up from brake switch area, over both wires until

it protects them from the switch plugs to top of airbox.

 

- crimp/solder on ground lug to wire that ends at 6mm airbox

 

- remove 6mm bolt, scratch off paint under bolt to ensure

electrical contact (as threaded insert in airbox is isolated)

apply some dielectric grease to lug and reinstall under bolt.

 

- on the wire ends down by the new switch, install the silicone

insulating jackets and then crimp/solder on the appropriate

terminals to match the switch ends.

 

- plug in new brake switch to new terminal ends

 

- use cable ties to secure new wires from switch area to airbox area

so that they are away from swingarm motion, exhaust heat, and

the slide under seat anchor tabs.

 

- reinstall seat, start and test brake light.

 

 

Q: What is this about a resistor in the spark plug and boot?

 

A: Resistor type spark plugs and spark plug wires were introduced on cars a

long time ago to reduce radio interference, primarily on AM radios. If you

look up inside the spark plug boot, you will see a slot in the brass

portion that will accept a flat blade screwdriver. If you unscrew this

part, the resistor and a spring will come out (note the order they come

out). The resistor is about a 5000 ohm. Electricity will take the path of

least resistance, and so some people replace the resistor with an equal

length of brass or stainless steel rod (don't use steel or aluminum as they

can rust or corrode and provide a bad contact). Most spark plugs are

resistor type (e.g. the "R" in the part number) so you still will have some

resistance in the secondary ignition circuit anyway.

 

 

*** --------- Other Modifications ------------------ ***

 

Q: Is there an upgrade for the chain roller near the front sprocket?

 

A: Yes and no, depending on the year of your bike. The service manual

shows some early 400's had the chain roller running on a shaft off the

frame, with a trailer hitch or muscle car style hood pin holding it on.

On any newer 400, the chain roller is held on with a bolt and these can

be replaced with a bearing style roller. The stock roller is free to flop

around on a steel collar, and will wear against the frame plate that

supports it. An OEM Honda roller is available (part number 52158-KA3-831).

Several aftermarket companies also sell bearing chain rollers in colours!

When installing a bearing style roller, you may need to use a thin washer

the size of the inner bearing race between the bearing and mount so that

the outer race and wear material have enough clearance to the frame.

 

Q: What is the idea of the frame insulator under the tank?

 

A: Good question. I think it is a lame attempt at keeping the fuel tank

from the heat of the oil inside the frame. But it doesn't really stay

positioned well and it stops that section of the frame from cooling the

oil. So I tossed it out in favour of lining the inside of the tank tunnel

with reflective aluminum tape (credit where credit is due - original idea

of aluminum tape on the tank tunnel from Scott Summers). Aluminum tape

is available at most hardware stores (not to be confused with Red Green

Duct tape!!). Clean the tank well 1st.

 

Q: Why does my kickstand stick out so much?

 

A: Good question. I don't know, but there is nothing stopping you from

bending it slightly so that it follows the contour of the swingarm when

folded up. You will have to take it off the bike and may want to use heat

and try to spread the bend over a region rather than putting a kink in the

tubing. The XR650 has a black kickstand, so feel free to re-paint yours

black once you are done.

 

Q: Is there any way I can make my bike lighter?

 

A: Yes and no. The yes part is that there are some small things you can

do, and the no part is that they aren't going to be of any earth shattering

significance. Meaning that having a light weight bike needs to be a design

goal right from the drawing board, and you will never get your 1996 design

to weigh as little as the current crop of race oriented off road bikes. On

the other hand, you need to keep in mind that having the absolute lightest

weight parts can sometimes come at the cost of reliability, which is very

important on a trail bike (which is the 400's primary role these days).

 

An aftermarket pipe will probably shave off a few pounds off your bike

(and your wallet). You can remove the decompressor (see decompressor

question above) if you are one who never uses it. Replacing the odometer,

cable and hub drive with an electronic unit with a magnetic pickup and

hub spacer also saves a few ounces. An aftermarket shifter and brake

pedal made from aluminum will be much lighter than the stock thick heavy

steel units. When you have the brake pedal off, note that the link from

the pedal to the master cylinder has a funny extra ear on it. The one from

an XR650R (46504-MT8-006) doesn't have that, or you can remove yours.

An aluminum kickstand may also be worthwhile looking into.

 

You may also want to consider removing the rim-locks if you are primarily

doing dual sport riding and not running low tire pressures and/or getting

a lot of flats. Your wheels will be more closer to balanced without them

and tire changes are easier, but the tires may slip on the rims and tear

out the valve stems under high traction situations with low (less than

13 PSI) pressure. Stock rims have a knurling (texture) on the bead contact

area to help grip the tire. If you do this, I'd recommend getting or

fabricating a plug for the rim lock hole so that water doesn't have an easy

path in. (The rim lock hole is the smaller, the valve hole is the bigger.)

 

Keeping with the unsprung weight theme (but getting into the insignificant),

the "distance collar" on the back bolt of the rear caliper guard is steel

and of marginal value - you will need a shorter bolt (p/n 96300-06016-00).

If you carry a tool kit with a screwdriver or a 5mm allen key, you can

drill out all the weld on the end of the rear axle shaft and twist out the

steel bar that contacts the swingarm. (Since the bar is hard and will not

drill, you will have to use a smaller drill to get the rest of the weld

out before you can break it free.) This also stops the rear axle from

holding water when on the sidestand. When you have the axle out, you might

want to consider just how useful you think the stopper plate (52162-KF0-000)

under the RHS chain adjusting snail is.

 

*** ------ Part Numbers ---------- ***

 

Q: What is a fiche?

 

A: Short for microfiche - sheets of plastic with exploded views of the

sections of the bike, accompanied by all the part numbers. A magnifier and

projector built into one was used to view these sheets. Now it is

typically all on computer, but the name fiche is still used to describe it.

 

 

Q: Can I browse the fiche myself?

 

A: While other manufacturers have official fiche sites on the internet,

Honda has yet to do this. However there are some dealers who have taken it

upon themselves to do this. Sometimes they obsure the part numbers to try

and ensure that you will order from them and not someone else.

 

http://www.bike-parts.fr/

http://www.ronayers.com/

http://www.blackmarketparts.com

http://www.servicehonda.com

 

ServiceHonda has been praised by several for good pricing, and they also

offer interactive parts pricing where you can key in a part number and get

their price on it right away.

 

There is also an XR400 fiche in Spanish(!) in PDF format at

http://www.motomatsuo.com.br/download1.htm

 

Q: How do I make sense of the Honda part numbers?

 

A: For those who haven't noticed, part numbers are usually

grouped 5-3-3, with the 1st 5 giving a part description,

the middle group of 3 giving the bike (or car!) model, and

the last group of 3 giving a revision number (670 and

671 seem to appear here all too often). The 1st group of

5 is sub-divided in a 2-3 split between function and

componet. Function seems to be like 15=oiling system,

18=exhaust, 22=clutch, 23=transmission, etc etc.

If the part was made in different colours, then an

additional group of 2 for colour appears after the 5-3-3.

 

The list gives the middle group of three for all bikes.

If a part on your bike was simply re-used from a prior

bike, then the bike code of that part will be of the

prior bike and not your bike. For example, your shiny

new 2004 XR400R is a KCY bike code, but the covers to

adjust the valves are 12361-KK0-000, and the KK0 is

the bike code for a 1984 XR200R (Hey, what's 20 years...)

 

A full list of of all the bike 3 digit/letter model codes

(e.g. XR650R=MBN, XR400=KCY etc) was available at:

 

http://www.westernhillshonda.com/product-codes.pdf

 

Note that some generic parts, like bolts, washers, nuts,

carb jets and so on that are used on multiple bikes don't

necessarily follow the 5-3-3 rule. For example, common bolts

use a mid group of five to encode the diameter and length,

instead of the mid group of three which determines the model.

 

 

Q: What are the part numbers for the HRC kit?

 

A: The 1st number is the whole kit, and then it lists all the individual

parts. The carb setting kit is also broken down into individual parts.

 

No. PARTS NUMBER DESCRIPTION QTY

 

06100-NKK-000 ENGINE POWER UP KIT 1

 

1 00X32-NKK-000 SET-UP MANUAL P/L 1

2 11394-KCY-670 GASKET, R. COVER 1

3 12191-KCY-671 GASKET, CYLINDER 1

4 12251-KCY-671 GASKET, CYLINDER HEAD 1

5 12391-KCY-671 GASKET, HEAD COVER 1

6 13101-NKK-000 PISTON 1

7 14000-NKK-000 CAMSHAFT ASSY 1

8 22100-NKK-000 OUTER COMP, CLUTCH 1

9 22401-NKK-000 SPRING CLUTCH 5

10 23121-NKK-000 GEAR, PRIMARY DRIVE 1

11 31910-NKK-003 SPARK PLUG, R216-10 1

12 16020-NKK-000 SETTING KIT, CARBURATOR 1

(1) 16012-NKK-000 NEEDLE JET, SET (1)

(2) 99103-437-0550 JET, SLOW #55 (1)

(3) 99103-437-0580 JET, SLOW #58 (1)

(4) 99103-437-0600 JET, SLOW #60 (1)

(5) 99103-437-0650 JET, SLOW #65 (1)

(6) 99103-437-0680 JET, SLOW #68 (1)

(7) 99113-GHB-1600 JET, MAIN #160 (1)

(8) 99113-GHB-1620 JET, MAIN #162 (1)

(9) 99113-GHB-1650 JET, MAIN #165 (1)

(10) 99113-GHB-1680 JET, MAIN #168 (1)

(11) 99113-GHB-1700 JET, MAIN #170 (1)

 

 

I think the #62 pilot (slow) jet is absent from the list, since at the time

the kit was introduced, all 400's shipped with the #62 pilot jet. This is

no longer the case for 1998 and newer bikes though.

 

 

------ Changes and Upgrades Each Year. -------

 

 

Q: What changes and updates have been done over the years?

 

A: There have been several, but most of them are easily overlooked. The

bikes get new stickers every year, and occasionally new lettering on the

seat. I won't bother detailing cosmetic changes, other than noting the

bikes changed from NH-196 (Ross white) in 1999 to R-134 (Fighting Red)

in 2000. Frame changed colour too, from NH-262M to NH-146M (Accurate

Silver Metallic). There have been quite a few country specific jetting

changes as well, and they were already covered earlier in this document.

 

During 1996:

************

The oil pump drive gear and the clutch lifter pins were updated.

 

In 1997:

********

 

There are some hints that the 2nd gear upgrade happened here and not

in 2000 as listed below.

 

In 1998:

********

The biggest change was the exhaust tip and the airbox inlet duct.

The exhaust tip no longer had a slip in silencer part, but was instead

fixed at a 3/4" output size. The airbox duct used to be a two piece unit,

and now it was all one molded chunk of rubber. The idea of both of these

changes was to be non-removable restrictions so that they could install

leaner jetting without worrying that the end user would pull out the

restrictions and run the engine dangerously lean. So now you got a 52/142

instead of the 62/162 for pilot/main jets. California got even leaner jets,

while Europe bikes retained the 162 main.

 

A different CDI box and flywheel were found on North American 400s this

year. John Rushworth in his package of info seemed to think the newer

CDI ignition had less advance. The different flywheel might be for the

same reason, as the placement of the little metal strip on the outside of

the flywheel is what the CDI box uses as a reference to determine when to

spark. Note that the Europe/Aus (ED/U/DK) bikes retained the original CDI

box and flywheel. I can only guess that the ignition change was in

conjunction with the leaner jetting that North American bikes got.

 

The kickstart was beefed up a bit to prevent breakage. The forks were

changed, with the spring retainer that used to go under the damper

rod nut no longer being used (hence the different length springs).

The airbox lid had an extra bit added to it to hold the filter retainer

on once the lid was closed, as the 96/97 versions could silently eject

and let the filter fall into the airbox. Shock pivots were changed from

the older style spherical pivots to needle bearings.

 

In 1999:

********

The countershaft size was upped 1mm from 17mm to 18mm and hence some

c'shaft related gears/bushings/washers needed to be changed to fit too.

The kickstart spindle was also upped 2mm. The kickstart one is easy to spot.

Just look at the numbers on the black oil seal around the kickstarter shaft.

Newer seals are 20mm ID, (30mm OD); older ones are 18mm ID, (29mm OD).

Shaft shear failures were reported (yikes!), hence these updates. If you

have a 1998 or older with a shear failure, it might be worth looking into

the machining required to accept the newer parts. It seems the new kickstart

shaft meant a new kickstart lever for 1999 as well. Part way through the

year, they started using a new head gasket (12251-MBV-003).

 

In 2000:

********

Got an updated second gear set (drive and driven) in the transmission.

The newer gear part numbers end in 671 and should be backwards compatible

with older bikes. Although the information I have indicates this took

place in 2000, there is information on the internet that seems to indicate

the 2nd gear upgrade took place as early as 1997.

 

I am not aware of any other changes that took place after this.

 

 

References:

 

(1) 1996-2004 Honda XR400 Service manual.

 

(2) John Rushworth's "XR4FAQ_26Stuff.zip"

 

(3) Yahoo XR4 and XR400 discussion group archives

 

(4) ThumperTalk XR250/XR400 discussion group archives.

 

End

[deckard]

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Great info thanks