Bigger back sprocket for spring

[nlovern]

ey again. nathan here. Im going to get a bigger back sprocket and othwer stuff at tax time. I was wondering would i need to go up 2 or 4 teeth in back. i dont run my bike over 55 or 60.
My 82 XS is geared high. Starting out in first feels like second and with my wife on back i have to slip the clutch alot and then it will buck and kick till i get rollon good.
Its got alot of grunt once going.
I have a 106 chain. I didnt take the extra 2 links out so i should have plenty of length for a bigger sprocket.
Now at 55 my rpm is 3800. How much more will my rpm,s go up with either bigger sprocket?
Nathan

 

[Newagerocker]

What size rear sprocket do you have on there now? Stock is 34.

 

[nlovern]

Its the stcok one.. prob original. Bike got only 11,000 miles

 

[nj1639]

It's been a while since I've run stock gearing but that rpm seems low at 55mph. Might want to go out and count the teeth on that sprocket........

 

[retiredgentleman]

17 front and a 36 on the back would work quite well with your wife on the back seat. It's low gearing, so its OK up to 60 mph................not good for expressways.

 

[Newagerocker]

You could also just try a 16T front; can't go smaller than that or you might develop a chain kink. A front sprocket is cheaper than a rear, that'll save you some more for other goodies. Be sure to shorten the chain to 104 links if you go that route and make sure both upper and lower clutch adjustment is spot on.

 

[XSLeo]

RPM's change about 100 rpm for each tooth on the rear sprocket. On my 75 I'm running a 17/30 and at 55 mph is about 3400 rpm. On the 80 with the stock 17/34 it runs about 3800 at 55mph. 4 teeth different, 400 rpm different. 1 tooth=100 rpm.
So if you go from a 34 to a 36 tooth your rpms will be about 4000 at 55.
These are what my bikes show, yours may vary a bit.
Leo

 

[I am Carbon]

4000 rpm 17 front 38 rear = 50 mph = thats what my gps showed. you can get to 50 real fast though