Engine braking for 2 stroke bikes harmful??

[Hilminho]

Guys, juz wanna ask... is it true dat using engine braking for 2 stroke bikes is actually harmful to the engine? I had read dis in wikipedia...'...Engine braking in a two-stroke engine can be extremely harmful to the engine, because cylinder and piston lubricant is delivered to each cylinder mixed with fuel. Consequently, during engine braking, the engine starves not only of fuel but also lubricant, while parts reciprocate rapidly. Four-stroke engines typically have lubrication by an oil pump, independent of the throttle and fuel system'' so is it true?:confused:

[Raptor]

That is correct.

 

That is why its a good habit to blip the throttle first before downshifting on the 2 strokes especially when racing on the track.

 

When I race the little Y125Z, I am changing gears at 10,000 rpm and pulling till 13000 rpms before dropping the gears for the corners.... don't blip can easily cause the engine to starve of lubrication and sieze the piston.

 

But normal road riding the rpms are not that high so there is enough lubricant in the cylinder that you do not have to this blipping during downshifting.

 

Four strokers do not worry about this lack of lubrication because they have an oil sump and the oil pump to force lubricate the piston, cylinder and bearings.

 

And that is the other reason that the 2T pump is disabled on Y125Z coz going premix is safer just in case the 2T pump fails... and you won't want it failing on you at max rpm and at top speed. The results can be catastrophic.

[xXxRatedxXx]

That is correct.

 

That is why its a good habit to blip the throttle first before downshifting on the 2 strokes especially when racing on the track.

 

When I race the little Y125Z, I am changing gears at 10,000 rpm and pulling till 13000 rpms before dropping the gears for the corners.... don't blip can easily cause the engine to starve of lubrication and sieze the piston.

 

But normal road riding the rpms are not that high so there is enough lubricant in the cylinder that you do not have to this blipping during downshifting.

 

Four strokers do not worry about this lack of lubrication because they have an oil sump and the oil pump to force lubricate the piston, cylinder and bearings.

 

And that is the other reason that the 2T pump is disabled on Y125Z coz going premix is safer just in case the 2T pump fails... and you won't want it failing on you at max rpm and at top speed. The results can be catastrophic.

 

Fantastic info mr raptor

 

What involves "blipping" the throttle? opening it up abit and shutting it quickly?? I'm trying to visualise this under 13kRPM as you mentioned while downshifting.

 

I guess this also explains why so many young "peh-sters" get seized piston once in awhile...

[scubasimon]

i always blip my throttle...although not always smoothly...hehehe...its a skill!!! a lot easier to do in a car than on a bike

[Raptor]

Fantastic info mr raptor

 

What involves "blipping" the throttle? opening it up abit and shutting it quickly?? I'm trying to visualise this under 13kRPM as you mentioned while downshifting.

 

I guess this also explains why so many young "peh-sters" get seized piston once in awhile...

 

Simultaneous quick movement of clutching in, close throttle, downshifting and giving it a quick twist of gas and releasing the clutch and repeat if going to downshift again.

 

Four strokers tend to do the same when downshifting from high rpms because blipping the throttle will bring the rpm higher to match the lower gear so that there will be no rear wheel lock and fishtailing during braking for the corners. Four strokers have much more engine braking torque than 2 strokers. To prevent rear wheel locks during sudden downshifts... a slipper clutch is the answer... it will slip the clutch and release the rear wheel so that it does not lock.

 

Two strokers do not have strong engine braking so its like riding a 4 stroker with a slipper clutch. Which is why 2 strokers tend to go into the corners faster coz when you close the throttle, the bike is still flying unlike a 4 stroker which will slow down very fast to a point you are too slow for the corner.

[Raptor]

i always blip my throttle...although not always smoothly...hehehe...its a skill!!! a lot easier to do in a car than on a bike

 

Try doing it while braking hard on the front brakes for the corner... its not easy.

[scubasimon]

for me, it is absolutely difficult on a bike...even when in very easy straight line braking for traffic lights (since i always shift sequentially). so i can imagine on a track will be a thousand times harder.

 

for me, the position of the brake lever is also very critical...when too high or too low, blipping is exceptionally difficult...is there a magic position?

[CyanSupra]

really?

I always like to use engine braking on my SP

Don't wanna waste the brake pads.

[rylche]

Can someone kindly explain the concept of blipping to the noobs like me here, please ?

[adesmond2]

errr.. i also always use engine braking.. so that means.. dun use is the best... correct?

[SparkerS1]

this thread is certainly making everyone confused regarding engine braking on a 2 stroker, haizzz, do wat u guys deem is best, i dun care liao:dozed:

[adesmond2]

this thread is certainly making everyone confused regarding engine braking on a 2 stroker, haizzz, do wat u guys deem is best, i dun care liao:dozed:

 

lolx.. yeah man.. ride 2 stroke for 2 years plus.. engine breaking seem "dangerous" in this thread.. care to give support for your statements?

[scubasimon]

blipping means when you downshift, twist the throttle to raise the RPM slightly so that when you engage a lower gear, the bike is still going smoothly as the engine braking effect is reduced. if you do not blip, the engine braking will be more pronounced.

 

see this article for explanation.

http://www.sportrider.com/ride/RSS/146_0402_shift_blip_throttle/index.html

 

as mentioned in earlier posts, engine braking on 2-strokers on the road is relatively harmless.

[zyrofillica]

as raptor said, if you are going at high rpms and wanna downshift, do a blip to inject more 2t lubrication into your cylinder. But if you are riding normally on the road, there is no need to carry this procedure out as your normal premix or pump mixture would provide sufficient lub.

 

Those who go to track or operate your 2 stroker at the high rpm range, pls consider changing to premix, use good 2t and mix a higher percentage of 2T to fuel to lub your cylinders. i think these are more important than carrying out the blipping manuever at every corner.

[Lim Ah Wan]

Okay So Give Us A Clear Example Can? I Getting More Confuse As I Read On.

 

So Lets Say I Am Approaching A Red Light Junction. What Should I Do?

 

Clutch In And Brake All The Way Then When Almost Reaching To A Stop Then Drop To Gear One or What? Hahaha.

[Hilminho]

Seriously, im confused too.... what should i do when going down a slope without using engine braking?

[scubasimon]

read the link that i posted.

[xXxRatedxXx]

what raptor is trying to say i think, is that all this engine braking and blipping is performed in the context of 2 stroke racing where the RPM is always very high when shifting down. Normal street riding engine brake shouldn't be dangerously harmful unless the 2T mix got problem (i.e. pump faulty, not enough 2t in premix).

 

Pls correct me if wrong.

 

Oh and i have another question.... what are the possible common causes of piston seizure in 2 strokers? Cos i see alot of young people on their SP, KR, RxZ and whatnot testing top speed and then KABOOM!!! Would like to know more.....

Edited January 14, 2010 by xXxRatedxXx

[adesmond2]

blipping means when you downshift, twist the throttle to raise the RPM slightly so that when you engage a lower gear, the bike is still going smoothly as the engine braking effect is reduced. if you do not blip, the engine braking will be more pronounced.

 

see this article for explanation.

http://www.sportrider.com/ride/RSS/146_0402_shift_blip_throttle/index.html

 

as mentioned in earlier posts, engine braking on 2-strokers on the road is relatively harmless.

 

ok.. nice one.. understood.. maintain a certain amount of RPM and braking at the same time..

[scubasimon]

never top up 2T...or tune until too little 2T...or...

[adesmond2]

what raptor is trying to say i think, is that all this engine braking and blipping is performed in the context of 2 stroke racing where the RPM is always very high when shifting down. Normal street riding engine brake shouldn't be dangerously harmful unless the 2T mix got problem (i.e. pump faulty, not enough 2t in premix).

 

Pls correct me if wrong.

 

Oh and i have another question.... what are the possible common causes of piston seizure in 2 strokers? Cos i see alot of young people on their SP, KR, RxZ and whatnot testing top speed and then KABOOM!!! Would like to know more.....

 

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

[Kwijibo]

i guess if you're saying in the context of a long distance sprint for top speed, then not blipping doesn't seem to be the contributing factor of a seizure (piston). Most of them either seize their pistons way before reaching top speed or when they hold on the throttle a bit longer than the engine can take . Like whats been said by scubasimon, it may be the lack of lubrication in the combustion chamber.

[SparkerS1]

inexperienced rider prone to have these problems

[bernardk]

Blipping should be the term "Heel Toe" for car. Even thou im not riding a 2 stroke i still do use that on my normal ride. It makes the engine smoother during turns but you still have the power in hand to throttle off after the apex.

 

Cos if you dun do blipping, imagine you are at red line on third gear. you wanna down shift, clutch in, by the time your rpm should be quite low. and if you dun blip, you down shift, your lower gear engage will be like from a sudden low rpm to the speed you are doing which is near red line at that rpm. Which then you will feel a sudden excessive EngBrake. Which you dun want that sudden jerk in your turn.

 

did i interpret correctly Mr Raptor?

[adesmond2]

Blipping should be the term "Heel Toe" for car. Even thou im not riding a 2 stroke i still do use that on my normal ride. It makes the engine smoother during turns but you still have the power in hand to throttle off after the apex.

 

Cos if you dun do blipping, imagine you are at red line on third gear. you wanna down shift, clutch in, by the time your rpm should be quite low. and if you dun blip, you down shift, your lower gear engage will be like from a sudden low rpm to the speed you are doing which is near red line at that rpm. Which then you will feel a sudden excessive EngBrake. Which you dun want that sudden jerk in your turn.

 

did i interpret correctly Mr Raptor?

 

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