I've got a an '96 Indy 440 liquid cooled. It runs at a peak RPM of 8000 which I am trying to drop a little. The sticker says 7750 +/- 200 rpm. My question is what sustained RPM is too high or may damage the motor. I am talking about wide open for a few miles not just 1/2 mile. The motor has about 5000 miles on it. I know they are made to run at high RPM but what is too high?

Thank's

there made to run at what ever rpm they were designed to run at,2 miles is no problem,just as long as you have safe jetting ,it will run all day like that,don,t go over the rpm they recommend if its stock or you will be out of the power band and go slower,add weight to the clutch,to get your rpm down

When your engine grenades on you, that's a good sign of too many RPMs.

Thank's,
I am in the process of trying different weights to bring down the peak. I tried a primary spring with a little less rate it helped a little but still made it to 8k eventually. I do notice the acceleration dropping off when it gets over 7900 or so.

Yeah,
It's that grenading thing that worries me!

H_purple, what can you get for top end out of that snowmobile?

SD,
95 on the speedo in less than perfect conditions. I had 21/39 gears in it at the time.