Sustained RPM

dubepj

XS650 Enthusiast
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My bike is gear low. 17 tooth front and 36 Rear. That's stock for my 1984 SK Canadian model. So it revs quite high. What RPM do you guys like to cruise at. Is 5000 a bit high? Seems like it is to me. Pretty sure I'll have to get a 33 or 34 rear sprocket. Thanks everyone for the replies.
 
With a 17/32 I cruise right at 5000 rpm at 75ish with 16" rear wheel. My bike seems happiest above 4000 rpm and pulls best between 4k and 6k. Doesn't seem to mind mile plus runs at 7k.
 
I used to ride my SK on the QE2 everyday to work and back. 4500 - 5000 was a comfortable range to ride but slower than the rest of the traffic. Back then, I wanted different gearing. These days, I am not in hurry and the gearing is fine. I tried figuring out the perfect solution for this by looking at some curves, rpm/ bhp, and so on... That was a bit of a rabbit hole.
 
Dubepj, there's just no easy answer to your question. How much vibration the motor produces depends on state of tune, crank runout, and balance factors. Some motors are pretty smooth at 7K rpm and some shake like a dog passing peach pits north of 4500. Then there's the matter of proper torque settings on motor mounts, rider gear (how well boots and gloves isolate vibration), and, last but certainly not least, rider tolerance. But it's always better not to work the motor any harder than you have to. If the bike were mine I'd install a 34 tooth rear sprocket; I found the 17F-34R combination to work quite well on gravel roads back in the day before our local politicians started harvesting contributions by passing work to their contractor pals to pave everything that couldn't get up and run.
 
I had 18/34 on my 78, up from 17/34. Just a couple hundred rpms less at 65. The limit was 55 back then, I was a broke USMC Corporal and couldn't afford more mods and wife in Phoenix and I in Yuma made the long trip often.
 
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