Author Topic: Stock sprockets and road speed  (Read 338 times)

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Offline socal1200r

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Stock sprockets and road speed
« on: January 21, 2015, 01:18:11 PM »
I noticed that when I'm doing 60mph, the engine is turning at 5000 rpms, which seems a little high to me.  I looked thru the pdf files for the Owner's Manual and workshop manual, but didn't find anything that said how many teeth are on the stock rear sprocket (maybe I missed it?).  I know the more teeth it has it will be quicker, which will result in higher rpms at the same road speed compared to a sprocket with less teeth, and of course the reverse is true for the front sprocket.  Back in my crotch rocket days, we'd usually go up two or three teeth on the rear sprocket, or down a tooth on the front, to make it accelerate a little quicker, at the expense of turning higher rpms on the freeway.   

Can anyone tell me how many teeth are on the stock sprocket for a '79 CB650, and if 5000 rpms at 60mph is about right, or too high, or?  Probably the next thing on my "to do" list will be a new chain and sprockets, so I want to make sure I get the right ones. 

Thanks

Offline Whaleman

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Re: Stock sprockets and road speed
« Reply #1 on: January 21, 2015, 01:35:30 PM »
Standard was 16 tooth front and 40 tooth rear. You must also compare what tires you have compared to stock. Front tire changes speed and rear tire changes how far you go per revolution.   3.14 times diameter will give you the length of one revolution. use the chart to compare the stock tire to what you now have. Dan