general tech question

What kind of problems would cause the RPM to rev too high on a sportbike?

Over-enthusiastic rider.

Well, this is at low MPH (around 35MPH). I bike is running at 90000RPM. I doubt its the way I'm shifting because I'm still running that hot in 4th gear. It's an 89 Kawa ZX6.

I don't quite follow what you are saying.

Is it revving in neutral?
Is it taking 9000 rpm to get to 35?
Is it not making power below this?
Is it revving without you adding throttle?

By the way, I had an 87 ZX750, close, but not the same.

Sorry I wasn't more clear. Here's the problem:

When she's all warmed up with out choke it take 9000 RPM for her to hold around 35 to 40 MPH in 4th gear and it take even more RPM for her to go to a high MPH. Now, I've been told that its not really a good idea to ride at 9000 RPM. So, is this a technical issue that needs to be corrected or is this normal. I'm a novice to riding so I'm not sure.

You said your 87 ZX750 was did the same thing?

first idea.. does it SOUND like your bike is revving this high? or its the tachometer just indicating so?

was the bike like this when you got it or has it only just occured?

Oh, its definately reving high becuase the more throttle I try to give it, the louder it sceams at me. And it did just start happening. It was laid down once but not hard enough to do any real damage. In fact. it was at a stand-still when it fell in the grass. I'm going to put a new thermosat in it this weekend because it is also overheating and I'm almost sure that the solution for that problem. But I would love to see if I can correct the other problem while I'm at it since I nearly have to take the whole bike apart to get to the thermosat.

Thanks for your help

Almost sounds like a float or vaccuum problem. OR... is that the original clutch? Maybe the clutch is slipping?

... OR... is that the original clutch? Maybe the clutch is slipping?

I think the clutch needs to be looked at first.
If the bike were revving with a good clutch, the bike would be
going much faster, say 90mph.
Reasoning:
The gearing, on a linear graph, would show roadspeed at a given rpm.
The engine, regardless of power or throttle, would be at the same roadspeed for this given rpm.

So, if it is truely running at 9000
rpm's, the link from the crankshaft to the drive sprocket seems to be
the issue. IE> the clutch is not fully engaging.

Check this out, and let us know

Ok, I never thought about the clutch causing the problem. I will look at that this weekend and let you know what I find out. Thanks again everyone for your help.

I guess I'm learning alot more than I really wanted to with my first bike, but I guess thats not really a bad thing.