When was the last time you had it above 5000 rpm?

[kbmb02]

9 minutes ago, tzei said:

Everything under 5000 RPM is idle.

 

My vote for FAQ post of the day. -KB

[fastricky]

I would have no issue revving it to near redline every opportunity I can get but I find over 5k the revving gets less sewing-machine-smooth and not as pleasing. Below 5k, it's just butter. Does that tell anyone anything? I've always wondered if the motor needs balancing perhaps? 

[Oldtimerfahrer]

6 hours ago, fastricky said:

I've always wondered if the motor needs balancing perhaps? 

Maybe, like me, you might have a loose end or two allowing vibrations to transfer or the engine is not optimally fed/ignited. "Soft" engine or tranny mounts, the bracket/bushings holding the exhaust at the transmission, exhaust hangers, other spinning auxiliaries in the engine compartment (excess slop in the fan belt or distorted mechanical fan blade) can/will contribute to noise and vibration. The bushes on my exhaust were shot, transmitting vibration at higher rpm and the return springs on my carbs resonate at certain RPM 's. I have spun the engine to 7k without incident, but have been spending time addressing the little niggly issues that contribute to unnecessary noise/vibration.