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djo269

Does hitting the rev limiter hurt the engine?

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Does riding your bike in the higher rpms and hitting the rev limiter hurt the engine? Isn't the rev limiter there for a reason(to keep you from entering into rpms that would cause damage?) And another question that's a bit off topic: Does wheelspin equal acceleration loss? I am applying these questions towards my 03' yz450. thanks

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Hitting the rev limiter too much is not good for it. You shouldn't need to hit it anyway. Just go up one. Yes, breaking traction = less acceleration, but obviously sometimes can't be avoided.

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The rev limiter is there to prevent catastrophic failure and should not be used as a shift light. It might be quite possible to ride around on the rev limiter for some time before anything lets go, but it would surely wear some parts out much faster than normal.

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Hitting the rev limiter is not bad per say. The rev limiter itself does not do anything bad to your engine. But like others have said, running those rpms is not conducive to long engine life. It's not like there's a certian rpm where anything below it is fine and anything above it is bad. Every rev is another wear cycle on all the motor components and takes you that much closer to a component failure. On top of that, running at high rpms creates more heat and higher stresses on motor components further accelerating a failure.

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On the wheelspin question, the answer is a definitive maybe. On asphalt, maximum acceleration, whether positive, negative (braking), or lateral (cornering) is achieved at around 10-15% tire slippage, meaning, in the case of acceleration, that the rear tire is turning 15% faster than the road speed.

The same kind of thing is true in the dirt, but to varying degrees, depending on the soil involved. Quite often, maximum acceleration is reached at much greater amounts of wheelspin than on pavement. If you were to try to drive a stock car on a paved oval the way a sprint car or a flat tracker negotiates a turn on a dirt track, ten cars will drive right underneath you, but that's clearly the fast way around in the dirt. The difference is that you can't dig down into the tarmack.

You just have to kind feel for the maximum bite as you accelerate, but in general, some wheelspin will accelerate quicker than either too much, or none at all.

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Does riding your bike in the higher rpms and hitting the rev limiter hurt the engine? Isn't the rev limiter there for a reason(to keep you from entering into rpms that would cause damage?) And another question that's a bit off topic: Does wheelspin equal acceleration loss? I am applying these questions towards my 03' yz450. thanks

over time, yes hitting the rev limiter will damage motor....

03 is notorious for wheelspin...get a 4-5oz flywheel weight

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They have concrete launch pads so that the track managers don't have to groom the starting box 7 or 8 times a day, and to "equalize" the start for all competitors (without having to actually groom anything; makes it equally poor for everyone).

You start on a concrete pad, and I'll start in a groomed dirt box. As long as we're both running knobbies, I'll beat you every time.

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Thanks for disspelling that tangent. I have to wonder if Honda or any other manufacturer would have so many "valve issues" if they could somehow impart the discipline for people not to rev an engine to oblivion. If only we could ask valve springs their opinion on the matter. The manufacturers build in the rev limiter so: A; Racers can get the maximum out of the product. and B; So knuckle heads don't go out and immediately destroy a perfectly good motorcycle.

"You can't legislate morality" (or common sense).

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Thanks for disspelling that tangent. I have to wonder if Honda or any other manufacturer would have so many "valve issues" if they could somehow impart the discipline for people not to rev an engine to oblivion. If only we could ask valve springs their opinion on the matter. The manufacturers build in the rev limiter so: A; Racers can get the maximum out of the product. and B; So knuckle heads don't go out and immediately destroy a perfectly good motorcycle.

"You can't legislate morality" (or common sense).

:D

The power peak is at 10,800, the rev limit is at 13,500. Do you know where your RPM's are?

It kind of reminds me of when the Z28 first came out, equipped with a 302 V8. The car was very capable of exceeding 8500 rpm, although the red line was at 7000 or less, and there were no rev limiters then. Many a spode got behind the wheel of one and uttered the famous last words, "You gotta hear this! Watch the tach!" That's the real reason the Camaros all ended up with 350's.

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What is mechanically happening when you hit the rev limiter? Is it like a pop off vale on a compressor? I have never hit mine.

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What is mechanically happening when you hit the rev limiter? Is it like a pop off vale on a compressor? I have never hit mine.

All I can tell you is you stop accelerating.

Then again, maybe you do that at the power peak of 10,800 RPM? :D

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It cuts spark until the rpms come down below the established limit. Though I do agree that this will acclerate wear to some degree, most engines can handle tremendous abuse. I rode an R6 for 2 seasons that were always shifted at the limit (even though peak hp was slightly lower), never showed one sign of weakness. Much harder than you could possibly fathom on the street. Hitting the limiter actually eliminated the need to shift right before corners at times, bang the limiter it slows slightly and comes back on in the corner. Very cool.

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Not to add insult to injury, while the rev limiter is there, I have spoke to many people within the MX industry and have posted the same question. Hitting the rev limiter occasionally wont do any harm. While over use of the rev limiter, over time will cause excessive valve wear, and possible valve failure over time. While some aftermarket manufacturers make cdi boxes that will give you higher rpm's, you are once again adding even more stress to internals than what it was designed for. While someone who doesnt hit the rev limiter often might go months without having to re-shim their valves, someone who does hit the rev limiter often might be changing valves shims 2x as much, and ultimately replacing valves once they fall out of spec.

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On the side note: This question is directly releated to Newtons laws of motion.

Wheelspin is not a decrease of acceleration necessarily! It depends on your perspective!

Acceleration is the changing of the velocity of the object.

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