Originally Posted by supershaft
Piston speed is super safe until you are real close to 9000rpm. If your valves aren't floating and they shouldn't be with titanium spring retainers, rev it higher for more power. If it isn't making more power up there you still might be able to use the over rev to your advantage at some tracks. 336's have good usable over rev.
Revs - I've been lead to believe it's a bit unsafe to rev an Airhead too high, but my R65 loves to spin to 8,000rpm. I use it as an over rev when I have runaway wheelspin on gravel roads, better to let it go than risk an upshift or back off in a powerslide, but also when the red mist is down and shifting by ear, my shift point seems to be 8,000rpm. I've been reading about the Michel 850 kit for the R65, and they say it spins to 9,000rpm. So long as I have no valve bounce, is it ok to run them at these revs ?
It reminds me of the Honda XLV750 I had - max hp at 7,000, red line at 8,000 and limiter at 8,250. I had that bike on a dyno a couple of times and the power curve was exactly the same a Honda's - it only lost a couple of hp between 7,000 and 8,000rpm. I used the over rev on gravel too, but also to save wasted upshifts between corners on the road - let it spin out to 8,000 and then into the next corner. I'd like to do this with the R65 too.