Safe sustained RPM range?

[gsJack]

We use to run 70-75 mph indicated for 400 mile interstate days to get to the mountains to play.  With 4800 rpm @ 60 mph for a stock GS I had approx 4800x75/60x16/15=6400 rpm at 75 mph with my 15T front sprocket on my otherwise stock 97 GS.  With it's power peak at 8500 rpm and a torque peak at 7000 rpm I found that a 7000-9000 rpm range gave the best performance in the mountains and ran many hours at those rpm's.  Put 80k miles on that 97 GS and it still ran like new and was solid all the way but oil consumption increased more and more past 50k miles and it used a lot of oil at freeway speeds at 80k miles.  I found 4k rpm to be the minimum usable rpm on the 97 GS but my current stock 02 GS with 91k miles on it now will pull smoothly from 3k rpm with it's 3 circuit carbs.  Lugging an air cooled mc engine at too low an rpm will do far more damage than running it at higher rpm's.

[madjak30]

A good "Rule of Thumb" for sustained RPM on any bike is to keep the revs between 1/3 & 2/3 of redline...so on a GS...

Redline...10,500rpm
Sustained revs between...3500 - 7000rpm...

My bike...

Redline...5,500rpm
Sustained revs between...1833 - 3667rpm...(1800 - 3700ish)

This way you avoid "lugging" the engine, or over revving ~ which will lead to overheating...

Hope this is helpful...

Later.

[Kijona]

Thanks for all the input guys... 5.5k feels pretty good and then it gets a bit hummy (high-frequency vibration) at 6 and 6.5 but then smooths out again at 7k...on the highway 7k is an indicated 90+ so yeah! I guess it'll be okay.