Set up: Carb balancing

[Guest BoBOKik]

What is carb balancing?

 

Most bikes with more than one cylinder have separate carburettors delivering fuel mixture to each combustion chamber. These are linked so that when the throttle cable tugs one slide open, they all open. For smooth, efficient running it is critical that the action of the carbs is synchronised so the same amount of fuel/air mixture is delievered to each cylinder.

 

If the carbs open at different times, the cylinders will make varying amounts of power. This causes vibration, most noticebly at tickover. Throttle respnse and fuel consumption are also adversely affected by unsynchronised carbs.

 

Checking balancing

 

The difficulty of checking your carbs varies from bike-to-bike, depending on access. Twins can often be checked with the tankin place, but on four-cylinder bikes it'll have to come off to allow access from the above. Either way, one thing you'll definitely need is a set of vacuum gauges.

 

The gauges measure the air pressure in the carbs' intakes simultaneously (there is no vacuum, but a low pressure area is caused by the suction of the downward moving piston accelerating the air) showing up any differences. Gauges can have dial-type indicators or tubes of mercury (or a mercury subtitute - much like a bank of thermometers. For the home mechanic, the tube-type gauge is the best bet as these are relatively cheap and stay calibrated.

 

If youhave to remove the tank, block the smaller of the pipes leading to the fuel tap. Unless you make up a dummy tank to deliver fuel, you'll have only the time offered by a carb's-worth of fuel in which to do the check. A washing-up liquid bottle can be used to refuel, but using bike's tank - with the fuel tap in teh RES position - and an extra-long pipe, is a better and safer option.

 

Each inlet rubber (engine side of carb) has a screw in it, or a short pipe capped by a rubber stopper (though one often carries the vacuum pipe back to the ruel tap) and these must be removed. Then, with the help of adaptors supplied with the gauges, eash inlet is connected to the gauges by a rubber pipe. The engine must be at operating temperture for the checking. If the readings are the same for all cylinders, great. If not, they'll need a tweak.

 

Adjustment

 

The aim is to have a 'datum' carb that is not adjusted, then balance the other carbs to it. Using the screws on the throttle linkages, starting nearest the datum carb, adjust the others until they are all the same. The correct-sized, long-shafted screwdriver is essential as the screws are easily chewed and forcing one will open the throttle and mess up the readings.

 

When you're happy that the carbs are in balance, blip the throttle, re-check them and re-set tickover, before putting everything back togather. Be very sure to replacethe screws/caps on the inlet stubs or it'll run like a bag of the smelly stuff.

 

Is it really worth doing?

 

Typically, carbs need balancing every 8000 miles (12,800 KM), however, with a manual, the instructions for the gauges and some patience, most folk could accomplish the task and it's super-satisfying to get right. On a twin cylinder bike, with just the one balancing screw, it's a much easier job than on a four.

 

Extracts from Bike March 03

[SRADR200]

so do u have any good advice for my small DR200 , carb washed recently but now difficult to start + rpm a bit high when reach destination . ... it wasn't like tat before. . . .

anyway wat's the purpose for the clip slots along top of main jet ? will there be any help to adjust the clip position ?

[nixe]

Hi,

If I am not wrong, the DR200 has only got one engine therefore 1 Carb. So there's no balancing to be done 'casue typically you balance the carbs so that they are synchronised.

 

Cheers.

[S750WP]

Check out this site with pictures on how to balance the carb

 

http://www.motorcyclistonline.com/howto/howtocarbs/

[KuKuBird]

how offen do we need to wash carb?

[SMOKEY]

Originally posted by SRADR200@Apr 19 2003, 02:22 AM

so do u have any good advice for my small DR200 , carb washed recently but now difficult to start + rpm a bit high when reach destination . ... it wasn't like tat before. . . .

anyway wat's the purpose for the clip slots along top of main jet ? will there be any help to adjust the clip position ?

reduce your idling speed.

[Chaoz]

does this inbalance of carburetor cause power loss, only 3 pistons running instead of 4 at certain rpm and extremely high fuel consumption?

[Chaoz]

is it for bikes with 1 carb and 4 pistons or many carbs and many pistons?

[xiwang315]

That is one cool projection clock!

 

 

This clock projects the time, date, or temp on the wall or ceiling http://www.liangdianup.com/clocks_1.htm some people call

it a ceiling clock but I call it a digital projection clock. I got the black one because at the time that was the only color

they had. But now they have them in black and also in white.

[yinghai]

two vacuum gauge will do the job..

[sky23]

wats the use of vacuum pls pm me thanks

[yinghai]

what the use of tuning or whats the use of the gauge?

[scoobydoo]

two vacuum gauge will do the job..

where can i buy the gauges in sinkapor

[Simon Soh]

where can i buy the gauges in sinkapor

 

try search for CarbTune in the web, u got to order it online.... it's a manometer with four column. single cyclinder bike no requirement to get synchronised aka balance.

 

there r ways of doing it, the result will be fruitfull if u know ur bike peak operating temperature & capture its synchn precisely at that point.

[newcomer]

I ordered the morgan carbtune last week for US80 shipped, waiting for it to arrive.

[mdjww]

i have checked it’s really great

[JbAtRaCeR]

Hi guys,want to check with you. Is it possible to balance the carb's butterfly opening by using a feeler gauge instead of using the vaccum meter?..

[Alu Andy]

Hi guys,want to check with you. Is it possible to balance the carb's butterfly opening by using a feeler gauge instead of using the vaccum meter?..

 

FAIZ!!!

ni zul ingat tak? at1a

amacam... kao bole tlg setting carb aku???

[newcomer]

nope can't. you'll get close if you use strips of newspaper, still a vacuum gauge aka carb balancer does the job better because extremely minute shifts in the butterfly will affect the balance.

unfortuantely i sold mine off otherwise i could help you, if i have the time.

[raven77]

like to know the direction for tuning the Air fuel screw at the carb rich turn clkwise & lean turn anti-clkwise. for a wave s .is it correct?

[creedmaniac]

so does my s4 got carb balancing problem?it virbrate only at right side at certain rpm...

[ngayxua]

We have many different trips through Panama, search our options below for the tour that's perfect for you.

 

 

adventure guided tours

adventure travel

[traz161616]

Any advice on a good place to balance the carburetters for an intruder? (tried doing it myself but maybe not so good)

[laneige]

The energy loss caused by the imbalance of the carburetor, only 3 and 4 is not the piston operation in a certain speed and high fuel consumption?

[dhmpap]

The explain it well here http://www.morebikes.co.uk/8615/balance-carbs-motorcycle/ - some videos there too