2 stroke engine braking. Myth or Fact?

So what do you guys believe/think about it? Bad? Ok? Let me know!

For me it doesn't exist lol. I primarily ride track on my 450. I also have a yz250 2 stroke setup woods. Going from the 450 to the 2 stroke I have a really hard time making turns because I just can't get slowed down enough. Even being really hard on both brakes I still can't slow it down. Now it's perfect for riding trails. There is no need to constantly be on the gas.

I'm curious to hear what others have to say about engine braking on a 2 stroke. The salesman I bought my 450 from was an old time 2 stroke racer. He never liked the 4 strokes because of so much engine braking. After 2 to 3 rides being on a 4 stroke I noticed I was making a lot of new inside lines that I could never get into before. They are 2 completely different beast

At lower engine speeds not a problem, say going down at tricky trail section in 1st gear with the engine revving a bit higher than idle speed.

Even at 50:1, that is way more oil than required for such low rpms.

 

The problem is shutting off the throttle at higher rpms after a hard pull and 'compression braking

or even worse downshifting a gear to decelerate even more.

 

At the time the piston is hot from the hard pull, you are making the engine spins fast

yet without any throttle shutting off the gas/oil which has an internal cooling effect.

The already hot piston keeps expanding into the bore.

 

EDIT: I understood the OP/question as is it good or bad for the engine, not related to riding style

Edited by mlatour

Just personal preference really. Riding style for both bikes is really different, kind of applesnand oranges. I will say that i can make insides of turns no problems on my cr250. Very new nimble capable bike. I prefer as little engine braking as possible.

Very little coasting into corners was biggest difference to me going from twostroke- fourstoke 

When I turn the throttle off on my CR250 it slows down.

the rear brake will slow you down a lot faster...

If you ride both often enough it's not really an issue either way, you adjust. Most strong opinions about it are people used to riding one then switching to the other for not enough time to make the adjustment. 

Just a bit of info in ride woods which is somewhat technical. Its more tight long trails so i engine brake unless im going down a hill and pull the clutch in so my bike wont stall jamming the rear brake down.

It seems like most people are missing the OP's question.  People say that engine braking on a 2 stroke is bad because you are spinning moderate to high RPM with the throttle closed.  Since a two stroke's rings, rod bearings and main bearing are lubricated by oil in the fuel, the theory is under engine braking you may not be supplying enough oil to the rings, rod bearings and main bearings and could potentially do damage.

To throw another wrinkle in, I wonder if the two stroke oil injection systems change that equation at all.  Do they inject more oil at higher RPM even when the throttle is closed?

I don't know the answer and I've never worried about it much because I naturally do very little engine braking.  The second I chop the throttle I pull the clutch out of habit.  Even on my 4 stroke, I don't engine brake because I'd usually be on the brakes and a root, rock or rut can cause the back to lock up and stall the motor if the clutch is out.

Doc

Edited by Doc_d

I never had a problem with any of the two strokes I've owned, including a couple of roadies, and an IT175 (waaaaay back) that I used lots on the road, where you shut off the throttle without pulling the clutch when slowing down for ages.

Also pretty much any 2 stroke I've pulled apart has a light coat of oil on everything, so they keep lubed for a little while anyway.

Must be someone on here that desert races a smoker that has experienced a seizure from lack of lube IF the problem exists....

Edited by DEATH_INC.

Maybe if you came down pikes peak off throttle but not normal riding. Pre mix tests  can take 20 minutes of running to fully clear the case of the previous oil or ratio.   Of bigger concern is making a hard long wfo pull thenn rolling off into the midrange area where ignition is most advanced and fueling can be lean.

16 hours ago, RidingWithStyle said:

 

So what do you guys believe/think about it? Bad? Ok? Let me know!

 

Never had it on a 2 stroke, never needed it on a 2 stroke.:excuseme:

100% confident that engine braking won't seize the bike. Never hear of or seen it happen, just heard people's theories trying to explain something that never happens.

Perhaps seize only in extreme / specific conditions but

if done on a regular basis at high rpm no doubt contribute to undue wear.

Edited by mlatour
Just now, mlatour said:

 

if done on a regular basis at high rpm no doubt contribute to undue wear.

I find it hard to believe.  Are there any studies or real evidence out there?

My YZ125 sees flat track and also supermoto duty occasionally.  Haven't seen anything unusual that I would't expect from a ridden hard 125.  My 450 has a slipper clutch and my 125 doesn't so I have on occasion been way to aggressive on my downshifts and engine breaking on corner entry. Probably not the ideal thing to do but I have not seen any lean issues from high rpm closed throttle.  Granted it is usually only for a few seconds max but a couple times a lap.

 

It's true; it exists! :prof:

I ran a lean pilot in my KTM 200XC for years without a problem.  Handed my bike over to a four stroke buddy that aggressively downshifted it on an MX track.  He was having a blast since it was his first time riding a 2 stroke.  Seized the big end rod bearing in about 2 minutes downshifting off a jump into a corner.  He only used front brake and engine braking.  Never saw someone ride a 2 stroke like that.  Made me cringe before it locked up.  Keep the recommended pilot and adjust your needle and main if you have to.  My 2 cents.

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