What is overrev, and how does it pertain to motorcycles?
the rev limiter prevents the bike from over reving.
look at a tachometer you see a redline. any rpm's over this redline and you are overriving the engine. this is bad because at this speed, the engine is not making more power. the valves begin to float. a lot of wear and tear is going on in the engine. keep it up long enough and you might see a piston fly out of the head or a connecting rod blow out of the side of the case.
when it gets ready to go BOOOOMMMM!!!!!
I think what the magazines mean by over-rev is that the bike doesn't fall off in HP quickly after the peak HP is achieved. Most motors usually have an ideal RPM range for power that you want to be in that falls short of the redline/rev limiter. If a motor has good over-rev, that means you can carry a gear a little longer for situations in which you may not want to upshift because you would be downshifting almost immediately after for an obstacle. As an example, say you drive out of a 2nd gear turn and are accelerating down a straight. You have a nice 3rd gear corner coming up, but the distance from the turn is such that you almost want to shift to 4th for a little extra drive, but you will have to back it down just a little and shift back to 3rd for the corner. If your bike has good over-rev, you can just keep it in 3rd because the bike keeps pulling 3rd even if you are past the ideal shift point.
Thanks cbus. That was exactly what I was looking for. I knew what "over reving" was, but that did not make sense in the context I kept reading it in.
too cool cbus..we were talking about the exact thing, not about over-rev itself but the ideal shifting point and places on the track where you almost want to upshift..thank god my 250f pulls that extra lil bit in 3rd !
Also, the ability to pull a taller gear is the same principle, but on the other end of the power band. That's why 2-strokes seam so "peaky". They don't really make much power on either side the sweet spot. Check out the dyno graphs that show up in any of the magazines and you'll see what I'm talking about. The 4 strokes smoothly build to the peak and then smoothly taper off. That characteristic makes a 4-stroke motor much more flexible in how they can be ridden. Its also why your average rider can ride a 4-stroke MX bike faster. Its not the peak HP but the nice spread of power over a wider RPM range.
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