Hmmnnn................ Well, as much as the assumption here (so far) seems to be that running at much lower RPM is some kind of cheap insurance for your engine, I beg to differ. Your bike was designed to perform at it's peak with standard gearing, so 4000 Rpm at 60 MPH is about right, give or take 500 RPM in either direction.
There is no evidence that I have seen to suggest that running your engine at lower revs will somehow preserve your engine, and I would argue that raising your gearing to the example that Ron has given us will only
increase the wear to your clutch, primary drive and transmission, not to mention chain and sprockets, in fact, it'd be akin to constantly taking off from the lights in second or third gear. Try doing that a few times and imagine what that's doing to your bike. 70 MPH in first gear? Jeepers!
Now of course you don't want to run at the other extreme of the spectrum either, 60 Mph at 6000 or 7000 RPM would be a bit silly too on old bikes like ours , not to mention uncomfortable, but increasing your sprocket gearing per Ron's example is not good. To be fair to Ron, the final gearing ratio is reduced somewhat by the smaller rear wheel's OD, but it would still be a heck of a lot higher than what I would think would be safe over a long period, particularly if there was a lot of city riding involved.
I mentioned an 18/44 tooth combo in my earlier post, from memory that gave me about 3500 Rpm at 60 Mph, and that's about the highest I would go, as that would often necessitate a down change to maintain the momentum up a hill, particularly when carrying extra gear or a passenger, but I would think that unless you're heading to Bonneville for a land speed attempt over several miles, you wouldn't want to go much higher. Just my two cents worth, of course. Cheers, Terry.
