7500 rpm's at 65 mph is this normal ?

can anyone help me, what do i need to do to bring the rpm's down at 65 to 70 mph ? the bike is an 81 KZ550 LTD

Post edited by: mcintyreruss, at: 2007/09/29 22:57

That sounds pretty high to me. Are you positive your clutch isn't slipping a little? Ed

seems to shift okay, can it be the spockets sizes?

At 65 mph my shaft drive KZ550 is turning about 5400 RPM indicated. Either the sprockets have been changed, the tach isn't working or you're not in 6th gear.

Post edited by: oldcoldankles, at: 2007/09/30 09:36

The rpm's sound a bit high to me. Perhaps the previous owner changed the sprocket ratios on the bike for better acceleration, at the expense of top speed. This might explain the higher revs at highway speeds.

On the Kz650 the ratio was 16 teeth on the front sprocket and 42 on the rear sprocket if my memory serves me correctly. You might want to check your bike and compare it to the factory sprocket ration.

Cheers-Colin Firth-Ontario Canada

You should have a 16/40 front to rear sprocket combination according to the factory manual, and those RPM's should be lower at that speed. I'd go with the largest front, and the smallest rear that's available for your bike. I bet there's a 14 or 15 on the front, or your tachometer isn't working properly.

Post edited by: CoreyClough, at: 2007/09/30 03:07

thanks i'll check the spockets, but can there be any other problem that can cause this besides the ratio or the tach not working right, ok at 65 the rpms 7500 to 8000, but if i gas on it rpms will go up then drop down some at about 80 to 85 mph what's with that?

i found a 13,14,15,16 front and 38,40,42 rear sprocket which ratio is best to fix my problem, oem is 16/38 ratio

mcintyreruss wrote:

thanks i'll check the spockets, but can there be any other problem that can cause this besides the ratio or the tach not working right, ok at 65 the rpms 7500 to 8000, but if i gas on it rpms will go up then drop down some at about 80 to 85 mph what's with that?

That sounds like clutch slippage. Make sure your cable is properly adjusted. Also, what kind of oil ar you using? (Certian "energy conserving" oils cause clutch slippage.) If none of the above is the problem, you need either new clutch springs, clutch plates, or both. Replacement is not too difficlut, and the parts are readily available and inexpensive. Replace the cover gasket too.

does that explain why at higher speeds, the rpms drop?

65 mph 7500 as i gas on it rpms go up and then drops down as i gas on it more

Post edited by: mcintyreruss, at: 2007/09/30 15:10

If not already done, would adjust clutch push-rod. Thereafter, would also double-check slack in clutch cable.

I verified information today with the 17/38 sprockets on my GPz. 5000 RPM at 80 MPH in 6th gear.