KZ650 gearing options

Hi!

I currently run a 40T rear sprocket instead of the stock 42T. I haven't counted the number of teeth on the front sprocket, but I presume it's the stock 16T. No larger front sprocket will fit the the standard protection rim/guard in place from what I can see.

According to Cycle, stock gearing should bring 4730 rpm @ 60 mph in 5th gear. With a 40T rear sprocket rpm should drop do 4500 rpm, and that's exactly what my tacho reads at an indicated 60. Which is still way too much for comfort. 5th is useful from 30 mph and I do feel like putting it in top gear at 40 mph at the latest. So calming it down is a priority.

Hence I'd like a 36T rear sprocket, which would bring rpm down to 4050 at 60 in top gear, but so far I haven't found anybody listing anything smaller than 38T.

I could run an 18T together with my 40T rear and get 4000 rpm @ 60, but I cannot see how it will fit. Can I remove the guard and run an 18T without any other clearance issues? Or run a 17/38 combo?

Stock 16/42 gearing puts 60mph @ 4500 rpm (see Kawasaki Service Manual). A 17 tooth front sprocket is available for the KZ650 - Kawasaki part number 13144-1009. Ed

Thanks, Ed. 17/38 should suit my needs well. If 4500 @ 60 is correct for the stock gearing, the data listed in Cycle's test from 1976 is wrong - as they well may be. Cycle World claimed 4612 rpm in their test from '77. Also means my tach is quite a bit optimistic as I already know the speedo reads a bit fast.

This site lists from 13 to 18T fronts and 38/40/42/45T rears www.motorcycleproducts.co.uk/catalogue/1...-3398_3726_3728.html