Maxed Out RPMs: Problem??

motoholic

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Hey all!

I was getting on the highway today and was making sure I didn't get hit by the cars next to and behind me and didn't watch my RPMs. I accidentally maxed out my RPMs in first gear. The only reason I know this is that there was a brief, sudden deceleration. It might be my imagination, but it seems like the engine is slightly sluggish now, even when in neutral and blipping the throttle. However, shifting is seemingly much smoother, now.:confused:

Anyone know if I might have done some damage or if there is some sort of inhibitor on the bike which might have caused some of the above symptoms? Any information would be greatly appreciated as I don't own a car and this is my only way to get around.

Thanks!
 

FzPilot

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Unless your bike is in it's very early brake-in stage (and I mean very very early) you have nothing to worry about.

You felt deceleration because you've ran the RPMs to it's rev limiter, that is actually there to protect your engine from over-revving.


Cheers,
 

Guitar Man

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I think you will be OK. If you pegged it off the rev limiter as soon as you started it up I would think that is the senario that would cause the most damage.
 

DefyInertia

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Dude, I've done it a hundred times...it's all good. Just don't blow past 14K on downshifts as there is no rev limiter to save you there...purely mechanical.
 

rsw81

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Believe it or not, bouncing off the rev-limiter is incredibly bad for the valve train of any engine. It is there to prevent you from over revving the engine which can cause the valves to float, due to inferior valve spring ratings to engine speed. Bouncing off the rev limiter causes sudden changes in engine rpm which is almost just as bad as it puts a lot of strain on the valve train to sudden change speeds like that, instead of the normal gradual change in speed.
If you did any damage, you'd know it 'cause the bike would really run like crap. You'd get poor compression, and thus poor combustion. If the bike generally feels like it is running alright, I wouldn't worry about it. Doing this once in a while will not likely do any damage, but I wouldn't make a habit of it.
 

DefyInertia

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Believe it or not, bouncing off the rev-limiter is incredibly bad for the valve train of any engine. It is there to prevent you from over revving the engine which can cause the valves to float, due to inferior valve spring ratings to engine speed. Bouncing off the rev limiter causes sudden changes in engine rpm which is almost just as bad as it puts a lot of strain on the valve train to sudden change speeds like that, instead of the normal gradual change in speed.

It's a 600cc I4, not a tuned to heaven vtec ricer. Do you realize how incredibly common bouncing off the rev limiter is (not that that prooves anything by itself)? And it does not cause significant "sudden changes". It's more like going from acceleration to 14, 14, 14, 14.

I would like to see some support for how this is "incredibly bad" for a modern sportbike. All it does is prevent you from gonig farther...it's not violent (revs, speed, chasis) at all.

EDIT - for some comic relief, all the squids around here greet each other by bouncing their engines off the rev limiter with the clutch pulled in...LOL!!
 
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rsw81

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It's a 600cc I4, not a tuned to heaven vtec ricer. Do you realize how incredibly common bouncing off the rev limiter is (not that that prooves anything by itself)? And it does not cause significant "sudden changes". It's more like going from acceleration to 14, 14, 14, 14.

I would like to see some support for how this is "incredibly bad" for a modern sportbike. All it does is prevent you from gonig farther...it's not violent (revs, speed, chasis) at all.

EDIT - for some comic relief, all the squids around here greet each other by bouncing their engines off the rev limiter with the clutch pulled in...LOL!!

Like you said, bouncing off the limiter with no resultant damage does not prove that it will not cause damage down the road if done repeatedly. I do not have a link of any proof of the damage that this does, but it is commonly known that bouncing off the rev limiter can and will cause connecting rods to compress, bend, and then break which of course leads to engine failure. This can also happen just from over-revving the engine as well. This is true of motorcycles, "tuned vtec rice rockets", american V8's, or any other engine that is not a rotary engine.

I don't think anyone on here needs proof that bouncing off the rev-limiter is a bad thing. If anyone is truly interested in knowing exactly why it is not recommended, I'll try harder to pull up articles on it for you.
 

DefyInertia

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I don't think anyone on here needs proof that bouncing off the rev-limiter is a bad thing. If anyone is truly interested in knowing exactly why it is not recommended, I'll try harder to pull up articles on it for you.

Yes, please do. I've NEVER heard that before (not that that proves anything...lol) :D
 

rsw81

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I can't find any reliable source of information, only forum threads about it. As such, take this information with a grain of salt, but it does make sense to me. If you know the inner workings of an engine, this will make sense.

1. Most people seem to say that bouncing off the rev limiter is fine.

2. Rev limiters are not entirely accurate and can allow engines to spin over the redline briefly, causing valves to risk float. This risks bending valve stems or even ejecting a rod through the block. (I find this one not very accurate as most engines are engineered to handle much more than the redline indicates)

3. The sudden change in acceleration/deceleration associated with bouncing off the rev limiter puts a lot of strain on the timing chain/belt. This can cause the chain to jump a tooth on the sprocket or cause the timing belt to slip a bit. This in turn causes the valve train to be improperly timed with the piston position --> piston hits valves --> bent valve stem, poor compression, bad combustion, etc. (This one makes the most sense to me given my knowledge of engine mechanics - I've been working on cars for ~15 years and they share the same basic mechanics with motorcycles)

In conclusion, I think it would be okay if it happens from time to time. No harm no foul. Repeated abuse in this regard I think will result in long term damage to the engine, specifically the valve train as mentioned in #3 above. For all we know, no damage will be caused in our engines. Only an engineer on the design team at Yamaha can give us a solid answer on this.
 

flyer34

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I think connecting rod damage wouldn't be very likely unless you dumped the clutch while bouncing off the rev limiter.

Valve float also shouldn't be an issue unless the engine is rather old and the valve springs have relaxed and/or the valve lash is out of adjustment.

There are generally two types of rev limiters on fuel injected engines: ignition-based and fuel-based. Fuel based rev limiters simply shut off fuel supply momentarily, resulting in an extremely lean mixture that can lead to detonation. Fox-body Mustangs had these and they caused problems. Ignition-based rev limiters shut off spark, which has a much more benign effect on the engine. I don't know which one the FZ6 has, but I would wager it has an ignition-based limiter.

A well-tuned and maintained engine shouldn't have any problems operating at max rpm. If it did, they would reduce the redline at the factory. Just don't dump the clutch while it's bouncing off the rev limiter. Max hp and torque usually occur well below max rpm, so there's usually not a performance reason to operate there anyway.

These are just my thoughts.
 

cashcrzzy

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Here is a good read ,, take note the best reason to have a rev limiter LAWN TURFING lol .. HAHA THE STORIES I COULD TELL YOU ABOUT THAT LOL
Rev limiter - Wikipedia, the free encyclopedia
I have worked on allot of engine`s in my time and have NEVER seen any damage done by JUST HITTING the rev limiter ... Now on older engine`s the engineers had no idea how to build them and valves were sloppy in the guide pistons floated around in the cylinder bore all the bearings were way too lose ,rods , cam ,mains the engine was so sloppy if you even came close to hitting red line :Note There Were No Rev Limiters Back Then : you COULD do damage . The tolerances are so tight in the newer engine`s the risk of doing damage is very slim unless you are in a no load situation . I am in no way saying to you to rip the limiter every time you ride .It is just another tool to stop the stupid people from destroying a work of art.
Greg A.
I Don't think The Question was never answered How many miles on your bike !!
 
S

sportrider

I think worrying about the connecting rods would be the last thing on your mind if you dumped the clutch while sitting on the rev limiter!!!

I hit the rev limiter fairly regularly... oh.... maybe thats why my bike is in the shop...:D



NOT
I can't wait to hear how it sounds on the rev limiter with my new stingers!!!:squid::D:squid::D:squid:
 
H

HavBlue

The sudden change in acceleration/deceleration associated with bouncing off the rev limiter puts a lot of strain on the timing chain/belt. This can cause the chain to jump a tooth on the sprocket or cause the timing belt to slip a bit. This in turn causes the valve train to be improperly timed with the piston position --> piston hits valves --> bent valve stem, poor compression, bad combustion, etc. (This one makes the most sense to me given my knowledge of engine mechanics - I've been working on cars for ~15 years and they share the same basic mechanics with motorcycles)


First, why is the rev limiter or governor there? It's there to prevent engine rotational speed from going beyond a predetermined design limitation. Fact is you could hold that engine right up against the limiter all day long and it would not likely damage that engine. If you look in the owner's manual on page it ain't there you will find "don't hit the rev limiter because it will damage the engine." The reason it isn't there is because it won't damage the engine. It's simply a safety designed into the BCU that prevents the ignition from allowing an appropriate spark to be generated beyond the predetermined limitations and it's that simple.

DI did bring up a good point in that it is a non-functioning unit on the deceleration side. Personally, I would like to see bikes have an adjustable shift light as well as the limiter....
 
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