Aprilia Riders

[trAmsU]

Originally posted by lacrimosae@Dec 8 2004, 03:09 AM

Full Arrow system is around $650-700.

erm...........wat do u mean by full system ah?????n how much difference can it make to the bike?????

[lacrimosae]

Tiramisu, this is for you.

 

Do take the time to read it will teach you how the 2-stroke engines work, and the need for a good exhaust system. (ie, it took me a long time to find this, so fekking read it yar?)

 

Ok, so you're thinking of getting an Aprilia, or any 2-stroker for that matter.

First of all, you need to understand that 2-strokers have three important advantages over four-stroke engines:

 

1) 2-stroke engines do not have valves, which simplifies their construction and lowers their weight.

2) 2-stroke engines fire once every revolution, while 4-stroke engines fire once every other revolution. This gives 2-stroke engines a significant power boost.

3) 2-stroke engines can work in any orientation, which can be important in something like a chainsaw. A standard 4-stroke engine may have problems with oil flow unless it is upright, and solving this problem can add complexity to the engine.

 

These advantages make 2-stroke engines lighter, simpler and less expensive to manufacture. 2-stroke engines also have the potential to pack about twice the power into the same space because there are twice as many power strokes per revolution. The combination of light weight and twice the power gives 2-stroke engines a great power-to-weight ratio compared to many 4-stroke engine designs.

 

You don't normally see 2-stroke engines in cars, however. That's because 2-stroke engines have a couple of significant disadvantages.

The gif below shows a typical cross flow design. You can see that 2-stroke engines overlap operations in order to reduce the part count.

 

Okay, let's run through the cycle starting with the point where the spark plug fires. As you read this, refer to the gif below.

Fuel and air in the cylinder have been compressed, and when the spark plug fires the mixture ignites. The resulting explosion drives the piston downward. Note that as the piston moves downward, it is compressing the air/fuel mixture in the crankcase. As the piston approaches the bottom of its stroke, the exhaust port is uncovered. The pressure in the cylinder drives most of the exhaust gases out of cylinder.

As the piston finally bottoms out, the intake port is uncovered. The piston's movement has pressurized the mixture in the crankcase, so it rushes into the cylinder, displacing the remaining exhaust gases and filling the cylinder with a fresh charge of fuel. Many 2-stroke engines that use a cross-flow design, the piston is shaped so that the incoming fuel mixture doesn't simply flow right over the top of the piston and out the exhaust port.

 

Now the momentum in the crankshaft starts driving the piston back toward the spark plug for the compression stroke. As the air/fuel mixture in the piston is compressed, a vacuum is created in the crankcase. This vacuum opens the reed valve and sucks air/fuel in from the carburetor.

Once the piston makes it to the end of the compression stroke, the spark plug fires again to repeat the cycle. It's called a 2-stoke engine because there is a compression stroke and then a combustion stroke. In a 4-stroke engine, there are separate intake, compression, combustion and exhaust strokes.

 

The piston is really doing three different things in a 2-stroke engine:

 

1) On one side of the piston is the combustion chamber, where the piston is compressing the air/fuel mixture and capturing the energy released by the ignition of the fuel.

2) On the other side of the piston is the crankcase, where the piston is creating a vacuum to suck in air/fuel from the carburetor through the reed valve and then pressurizing the crankcase so that air/fuel is forced into the combustion chamber.

3) Meanwhile, the sides of the piston are acting like valves, covering and uncovering the intake and exhaust ports drilled into the side of the cylinder wall.

 

This is why you have to mix special 2T in with the fuel.

In a 4-stroke engine, the crankcase is completely separate from the combustion chamber, so you can fill the crankcase with heavy oil to lubricate the crankshaft bearings, the bearings on either end of the piston's connecting rod and the cylinder wall.

In a 2-stroke engine, on the other hand, the crankcase is serving as a pressurization chamber to force air/fuel into the cylinder, so it can't hold a thick oil. Instead, you mix oil in with the petrol to lubricate the crankshaft, connecting rod and cylinder walls.

 

Notice that all 2-stroke bikes have a bulge in their exhaust pipe?

 

http://img.photobucket.com/albums/v260/lacrimosae/Aprilia/2-stroke.gif

 

That bulge is called an expansion chamber, and it is used to increase the horsepower of the engine. This technique only works on 2-stroke engines, which is why you see it on a lot of 2-stroke bikes.

 

The basic idea behind an expansion chamber is to use the momentum and pressure of the exhaust gases to create a pump that squeezes more air and fuel into the cylinder during the intake stroke. It does the same sort of thing that a turbocharger does, but it does it without moving parts.

 

The cross flow design is such so that the exhaust and intake parts of the cycle overlap. As the piston moves down, it uncovers the exhaust port first to let most of the exhaust out. Then it opens the intake port to let fuel/2T/air in. With a correctly-tuned expansion chamber in place, two things happen to help the intake process:

 

As the exhaust gases expand into the expansion chamber, they create a vacuum at the exhaust port. This vacuum pulls fuel/2T/air into the cylinder.

As the shock wave of the exhaust pulse hits the end of the expansion chamber, it echoes back, pushing any fuel/2T/air that got pulled through the exhaust port back into the cylinder.

 

By pulling extra fuel/2T/air through the cylinder and then pushing it back in, the expansion port has the effect of stuffing more fuel/2T/air into the cylinder on each stroke. This gives the engine extra power in the same way that a turbocharger does.

 

Arrow, and other aftermarket manufacturors of racing exhausts have constructed their pipes for optimal performance described above. Pre-99 versions of Aprilia models come equipped with the catalytic convertor (affectionately known as the 'milo kong'), which 'suffocates' the engine because of restricted exhaust flow. The engine does not reach optimal combustion conditions because of these hideous contraptions that LTA has ordered the bikes to be shipped over with. The standard RS pipes that come with post-Y2K versions and later do not function as well as racing exhausts, but better than the catalytc convertors.

 

For those of you who have not read a single word and simply skipped down to this last paragraph, all I can say is, You dont deserve to ride an Aprilia.'

[trAmsU]

hey..........thanx a lot for the info provided............thanx..........

 

 

:cheer: :cheer:

[servoprax]

Originally posted by t|rAm|sU@Dec 8 2004, 02:31 PM

hey..........thanx a lot for the info provided............thanx..........

 

 

:cheer: :cheer:

brand new arrow header pipe ( da stomach ) going for $350 without silencer. any takers ? silencer also available at another price but u can use those frm ahboy.

 

anyone wana mass order BRAKING sintered brakepads ?

 

anyone wana mass order anithing , let us know.

[lacrimosae]

Tiramisu,

Please use the Reply function, and not the Quote function coz it takes up server space and eats up bandwidth. Thanks.

:cheer:

[Marilyn_Manson]

Yo anybody now riding Rs125 number plate FM2272D? It's an Extrema model.

[rogie]

hi fellow aprilians...hvnt been posting 4 quite some time...having some family problems 4 d week...haiz...but its all settled...kopi tmr nite any1??hvnt meet up 4 a long time liaoz...

[kebeen]

Nice info lacrimosae

enjoyed that.

 

more if u guys R interested.

 

http://science.howstuffworks.com/two-stroke.htm

http://auto.howstuffworks.com/catalytic-converter.htm

[ROTHMANS]

how about this sat day let's have a outing? anyone, servo?

[fibre]

wah lao...so chim

 

anyway, how abt mass order for the slightly-better-but-not-so-expensive ferrodo pads? dont haf to be sintered , after all, u will finish them one day

[lacrimosae]

Sintered, and nothing less.

My baby deserves the best.

[d3an_cain]

Some 1 Selling his/her RSV mile R bike @garage sales..

 

RSV MILE R FOR SALE!!!

[Angel_of_sin]

hi i am looking for RS250 to COI . pls pm me with details.

[supertzm]

Hey ppl, letting go a aprilia r/s pipe for $80, if interested pm me or sms me at 97373969 thx

[trAmsU]

erm.....how much does it cost to change the seat of rs125 ah????/i rider seat.......anyone can tel mi???

[lacrimosae]

Originally posted by t|rAm|sU@Dec 10 2004, 05:39 PM

erm.....how much does it cost to change the seat of rs125 ah????/i rider seat.......anyone can tel mi???

I just sold off my single seater cowling.

Brand new, no crack, no scratch, gloss black with white stripes.

$150. Original is $180.

 

Heard the new owner very happy with it. Maybe can ask him to post some photos of it on his bike soon...

[fire_ufo]

Originally posted by lacrimosae@Dec 11 2004, 12:39 AM

 

Heard the new owner very happy with it. Maybe can ask him to post some photos of it on his bike soon...

The new owner (must) be a RS125 racer. :lovestruck:

[Guest CykeArtemis]

hi guys..

anyone knows whats wrong wif the bike? if it has that occasional knocking sound while running... engine sounds a bit like a scrambler now... and 2 days ago, suddenly my low rpm became very weak, until i hit 6k, suddenly have power again, sort of like the valve effect at 8k, except its at 6k...

heard from mech at gerry looi's that the bearings holding up my piston is damaged... and needs repair... or else i'll just get a piston jam.. any idea how much to get that done?

oh, and is ideal open on the weekends?

thanx for the help everyone...

 

ps anyone can tell the effect of piston jamming while on the move? issit wheels lock or wheels roll freely or just no power?

[fire_ufo]

Originally posted by CykeArtemis@Dec 11 2004, 03:11 AM

hi guys..

anyone knows whats wrong wif the bike? if it has that occasional knocking sound while running... engine sounds a bit like a scrambler now... and 2 days ago, suddenly my low rpm became very weak, until i hit 6k, suddenly have power again, sort of like the valve effect at 8k, except its at 6k...

heard from mech at gerry looi's that the bearings holding up my piston is damaged... and needs repair... or else i'll just get a piston jam.. any idea how much to get that done?

oh, and is ideal open on the weekends?

thanx for the help everyone...

 

ps anyone can tell the effect of piston jamming while on the move? issit wheels lock or wheels roll freely or just no power?

piston jamming is very dangerous, avoid it, if positable. cutah in if there is piston jamming, allow the bike to move in free wheeling. it may save ur life. :goodluck:

[eyz]

Originally posted by CykeArtemis@Dec 11 2004, 03:11 AM

hi guys..

anyone knows whats wrong wif the bike? if it has that occasional knocking sound while running... engine sounds a bit like a scrambler now... and 2 days ago, suddenly my low rpm became very weak, until i hit 6k, suddenly have power again, sort of like the valve effect at 8k, except its at 6k...

heard from mech at gerry looi's that the bearings holding up my piston is damaged... and needs repair... or else i'll just get a piston jam.. any idea how much to get that done?

oh, and is ideal open on the weekends?

thanx for the help everyone...

 

ps anyone can tell the effect of piston jamming while on the move? issit wheels lock or wheels roll freely or just no power?

bro, here an account of a fellow biker encounter when his bike had a piston seizure..

Read this!

 

This is only for your info, as your problem may not lie solely with the piston bearing. What I can advice you is that you bring your bike to a few mechanic to assess the situation before accepting what your bikeshop had told you. If I'm not wrong, to change the piston bearing, it would mean a full overhaul. And you don't change the bearing alone. You will usually change all other stuffs like you would do for a engine overhaul.

[DeusExMachina]

Originally posted by CykeArtemis@Dec 11 2004, 03:11 AM

hi guys..

anyone knows whats wrong wif the bike? if it has that occasional knocking sound while running... engine sounds a bit like a scrambler now... and 2 days ago, suddenly my low rpm became very weak, until i hit 6k, suddenly have power again, sort of like the valve effect at 8k, except its at 6k...

 

ps anyone can tell the effect of piston jamming while on the move? issit wheels lock or wheels roll freely or just no power?

 

 

First.... check your powervalve.

 

It might be jammed, or your power valve actuator might be faulty.

 

Always start small, and work your way up to the big problems. Don't blindly listen to mechanics that can't wait to charge you for bigger works.

 

 

So one by one, from small (less expensive) to big...

Check for:

- Power Valve jam

- Power valve actuator/solenoid working?

- RAVE (power valve control) unit working?

- Piston rings tight/loose/worn?

- Piston/conrod/bearings

[macerena]

Originally posted by lacrimosae@Dec 11 2004, 12:39 AM

Heard the new owner very happy with it. Maybe can ask him to post some photos of it on his bike soon...

Hang on Mr. Law, photos on the way..i want some comments on it too..

Damn the paint condition is so good, makes me feel like respraying the rest of my whole bike..hahaha..

[lacrimosae]

Originally posted by macerena@Dec 11 2004, 12:30 PM

Hang on Mr. Law, photos on the way..i want some comments on it too..

Damn the paint condition is so good, makes me feel like respraying the rest of my whole bike..hahaha..

Damn.... it looks so good on your bike, makes me wish I hadnt sold it, or sold it to you for more.... hahaha

 

Told you before, scratch-free, crack-free, etc. Its a brand new spray job.

Dont need to spray your bike lah...

If you respray your bike, its like buying a dog because you found some dog food.

[fibre]

Originally posted by CykeArtemis@Dec 11 2004, 03:11 AM

hi guys..

anyone knows whats wrong wif the bike? if it has that occasional knocking sound while running... engine sounds a bit like a scrambler now... and 2 days ago, suddenly my low rpm became very weak, until i hit 6k, suddenly have power again, sort of like the valve effect at 8k, except its at 6k...

heard from mech at gerry looi's that the bearings holding up my piston is damaged... and needs repair... or else i'll just get a piston jam.. any idea how much to get that done?

oh, and is ideal open on the weekends?

thanx for the help everyone...

 

ps anyone can tell the effect of piston jamming while on the move? issit wheels lock or wheels roll freely or just no power?

this sounds like worn piston rings to me, due to the loss of low speed power

but as the sounds come suddenly, it might be the main bearings;piston bearings almost never break down

 

First of all, clean ur valve and see if u still get ur low rev power back

if u do, den try not to ride it too hard anymore, and send it to workshop for big end overhaul

if power still the same, den should be the piston rings...

 

either ways, the best thing to do is to send it to a workshop to strip it down and check...thats the safest way...if u choose to wait and suey suey piston jam, den u might even haf to change block

 

anyway, good luck, and be careful

[Guest CykeArtemis]

hrrmmmmmm thanx guys for the advices...

think mon go down ideal... let them see... anyone wanna come? :þ

hopefully can make it there...

anyways, wad's the price range like if i have to change the piston bearings? or piston rings? if piston rings den dun need to strip the engine ah? or both need to strip engine?

 

Anyway, i really take my hats off to u guys who know so much about the bike... how u all get to know so much about it? i dun dare to unscrew anything off of the bike for fear that i can't put it back... but u guys seem to have ur own workshop at home

ahaha...

 

but no matter what

thanks again!