Engine braking for 2 stroke bikes harmful??

[bernardk]

just did that and it feels my gear are smoother.. but.. prone to be stared by other bikers..

 

Dun rev so much la Hahahahaha.... i dun think ppl will stare at you la dun worry. Its normal to do that.

[aRcHeR]

correct... most likely i guess because they nv do blipping...

 

2T not enough la..

[Raptor]

To understand all these... you must first understand how a carb works, the purpose of the pilot jet, main jet, needle taper and height setting and how they affect fuel/air ratio of the mixture that is going into the combustion chamber.

 

One must also understand how the pilot jet comes into play at idle to 1/4 throttle opening, main jet from 1/4 to 3/4 opening and how the needle taper and height setting and the size of the main jet affects the 3/4 to wide open throttle.

 

One must understand that the engine is basically an air pump, air drawn thru the carb and pumped out the exhaust. One must first understand the priniciples of airflow thru a venturi to understand carburation.

 

One must understand that removing the air filter or 'tonging' the exhaust makes the engine run lean, and although lean mixtures give good top speed power... but the down side is the engine runs very hot because heat is energy.

 

More energy produced= more heat.

 

More heat = to cheap 2T burning up instead of staying in liquid form to lubricate the piston and bearings = engine seize.

 

That is why you should not go cheap on 2T if you like to run your bike at redline rpms all the time.

 

When I was racing last year for Abboy Motor Racing on a Y125Z, I seized 3 pistons, destroyed 2 cylinder blocks, 2 gear boxes during practices.

 

Boy Johari, my mechanic, of Abboy Motor Racing starts me off by tuning the bike to the rich side. As I got used to the power of the bike and started clocking faster lap times.. he started to tune the bike leaner by changing the jets and needle position and I started to go faster and faster.

 

Then it became so lean that the engine will blow up after I set 5 fast laps at Tuas. Then he tunes it richer abit... and it blows up after 8 laps. Then he tunes it richer by a bit more and it blows up after 15 laps... and that was the setting we used for the races which were run at 12 laps.

 

And I dare to max the rpms out in the races coz I know the engine will only give up after 14 laps of hard racing.

 

So as for those who are just riding normally on the roads... there is no need to be concerned with not enough 2T to lubricate the engine... there is not enough heat produced to burn off the 2T. There is no requirement to blip the throttle when riding at legal speed limits on public roads.

 

But for those who just tong the exhaust or remove the sponge air filter... you are running leaner.. thats why you feel like the bike got quicker throttle response and faster pickup. Its still OK to do that for normal riding... but if you like to 2nd link and test top speed with other bikes... standby your wallet for a blown engine and engine overhaul.

 

There is more to racing and bike modifications for power and durability then just cutting an exhaust or putting on a bigger jet or carb.

 

My mechanic was a 2 stroke champion at PG himself before he became a full time mechanic and he knows how to tune the engine of the little Y125Z for max power. It takes experience.. and to me a good racer is a good tuner of bikes coz he knows what it is all about... and not all mechanics are racers before.

 

How good is his tuning?? Good enough for me to qualify on pole for all the races and finish on the podium in every race. That itself, speaks volumes of the skill of a mechanic.

Edited January 15, 2010 by Raptor

[adesmond2]

To understand all these... you must first understand how a carb works, the purpose of the pilot jet, main jet, needle taper and height setting and how they affect fuel/air ratio of the mixture that is going into the combustion chamber.

 

One must also understand how the pilot jet comes into play at idle to 1/4 throttle opening, main jet from 1/4 to 3/4 opening and how the needle taper and height setting and the size of the main jet affects the 3/4 to wide open throttle.

 

One must understand that the engine is basically an air pump, air drawn thru the carb and pumped out the exhaust. One must first understand the priniciples of airflow thru a venturi to understand carburation.

 

One must understand that removing the air filter or 'tonging' the exhaust makes the engine run lean, and although lean mixtures give good top speed power... but the down side is the engine runs very hot because heat is energy.

 

More energy produced= more heat.

 

More heat = to cheap 2T burning up instead of staying in liquid form to lubricate the piston and bearings = engine seize.

 

That is why you should not go cheap on 2T if you like to run your bike at redline rpms all the time.

 

When I was racing last year for Abboy Motor Racing on a Y125Z, I seized 3 pistons, destroyed 2 cylinder blocks, 2 gear boxes during practices.

 

Boy Johari, my mechanic, of Abboy Motor Racing starts me off by tuning the bike to the rich side. As I got used to the power of the bike and started clocking faster lap times.. he started to tune the bike leaner by changing the jets and needle position and I started to go faster and faster.

 

Then it became so lean that the engine will blow up after I set 5 fast laps at Tuas. Then he tunes it richer abit... and it blows up after 8 laps. Then he tunes it richer by a bit more and it blows up after 15 laps... and that was the setting we used for the races which were run at 12 laps.

 

And I dare to max the rpms out in the races coz I know the engine will only give up after 14 laps of hard racing.

 

So as for those who are just riding normally on the roads... there is no need to be concerned with not enough 2T to lubricate the engine... there is not enough heat produced to burn off the 2T. There is no requirement to blip the throttle when riding at legal speed limits on public roads.

 

But for those who just tong the exhaust or remove the sponge air filter... you are running leaner.. thats why you feel like the bike got quicker throttle response and faster pickup. Its still OK to do that for normal riding... but if you like to 2nd link and test top speed with other bikes... standby your wallet for a blown engine and engine overhaul.

 

There is more to racing and bike modifications for power and durability then just cutting an exhaust or putting on a bigger jet or carb.

 

My mechanic was a 2 stroke champion at PG himself before he became a full time mechanic and he knows how to tune the engine of the little Y125Z for max power. It takes experience.. and to me a good racer is a good tuner of bikes coz he knows what it is all about... and not all mechanics are racers before.

 

How good is his tuning?? Good enough for me to qualify on pole for all the races and finish on the podium in every race. That itself, speaks volumes of the skill of a mechanic.

 

good phrase..

[Zack939]

Well said!!

[h4hahak1m]

Raptor wad. Haha. Uncle racer

[Snoek]

Ups for raptor

[aaronlim_1]

hi guys! sp rider here. lol i always clutch in and let go at same gear until the speed drops den i down shift when slowing down at traffic lights 1 sia. cauz i dun like engine braking like waste fuel n might damage engine. i wonder if im wrong doin tis. hope the pros here can gif me sum advice haha!

[Raptor]

hi guys! sp rider here. lol i always clutch in and let go at same gear until the speed drops den i down shift when slowing down at traffic lights 1 sia. cauz i dun like engine braking like waste fuel n might damage engine. i wonder if im wrong doin tis. hope the pros here can gif me sum advice haha!

 

I am not a pro... but I do know abit about carburation.

 

Engine braking is with the throttle closed. How to waste fuel... unless your pilot jet is bigger than your main jet.

[kifakw]

if you do not shift down fast enough, the engine will rev from idle to the respective rpm or that speed/gear u're in?

[aaronlim_1]

its like if i downshift the rpm will rise ma rpm rise = piston rev more=consump more petrol

lol pls correct me if im wrong

Edited January 28, 2010 by Raptor

[Orleng]

aiya, engine brake puts more wear on drive parts, chain + sprockets + rear tyre. save brake pads.

 

use brakes, save drive parts, more wear on brake pads + disc.

 

take your pick.

 

only other thing is if alota uphill downhill then worry about brake fluid overheating lor. other than that, something's gonna wear one way or another!

 

ymmv.

[Raptor]

its like if i downshift the rpm will rise ma rpm rise = piston rev more=consump more petrol

lol pls correct me if im wrong

 

Wrong.

 

You are downshifting to slow down... even though your rpm climbs because of engine braking ie your rear wheel is now driving the engine.. your throttle is closed...the amount of fuel going is as good as when the bike is at idling.

 

Unless like on the track, downshifting is done to set the bike up for a quick accleration out of the corner, then the dowshifting will be with the throttle open to keep the rpms up... fuel is definitely going in.

[xXxRatedxXx]

Wrong.

 

You are downshifting to slow down... even though your rpm climbs because of engine braking ie your rear wheel is now driving the engine.. your throttle is closed...the amount of fuel going is as good as when the bike is at idling.

 

Unless like on the track, downshifting is done to set the bike up for a quick accleration out of the corner, then the dowshifting will be with the throttle open to keep the rpms up... fuel is definitely going in.

 

Interesting.... i never thought of it that way.... now i know!