Sprocket questions

[xander18]

Hey all,
I want a little more top end speed and efficiency on my long haul XS so I was going to play with the sprockets.

Can I put a larger front sprocket in without messing with my clutch push rod? If not, what would be a good size rear sprocket?

Thanks all,
Xander

 

[5twins]

You can only go up 1 tooth on the front from the stock 17 to an 18. Clearance is tight so an o-ring chain may or may not fit (depends on manufacturer). You also need to remove the shift shaft protector/chain guide. Personally, I don't feel the trade-off is worth it as you can achieve almost the same thing by changing the rear sprocket. You won't be able to get the absolute highest gearing available by changing just the rear but you have to realize - we're only dealing with a 50HP bike here. Gear it too high and it's a real dog off the line. You kill the "fun factor".

17-30 and 17-32 are very popular. An 18" rear wheel equates to about 1 tooth less on a 16". In other words, an 18" with a 33 will run about the same RPMs as a 16" with a 32, 32 on an 18" like a 31 on a 16", etc.

 

[pamcopete]

xander18,

Here is an Excel spreadsheet that shows RPM vs MPH for all combinations of sprockets, gears and wheels, including MikesXS overdrive 5th gear. Just click on the yellow cells to reveal a pull down with the value you want.

XS650 Revs

 

[WacoBrian]

You can only go up 1 tooth on the front from the stock 17 to an 18. Clearance is tight so an o-ring chain may or may not fit (depends on manufacturer). You also need to remove the shift shaft protector/chain guide. Personally, I don't feel the trade-off is worth it as you can achieve almost the same thing by changing the rear sprocket. You won't be able to get the absolute highest gearing available by changing just the rear but you have to realize - we're only dealing with a 50HP bike here. Gear it too high and it's a real dog off the line. You kill the "fun factor".

thats what i did just the back sprocket to a 31, not as quick but i live right off I-35 if i go anywere its highway time

 

[xander18]

Alright, I'll pass on messing with the front sprocket. I think I'll buy new sprockets anyway since I happen to have an IZUMI chain kicking around.

I only wanted to jump a tooth or maybe two on the rear sprocket, I'm not trying to make a huge difference. Just raise my comfortable top end 5 or 10 mph.

WacoBrian, 31 sounds like a good number then. Since this will be a roadtrip bike I'll have it pretty loaded, imagine the approx. weight of one and a half people (or one regular person and one girlfriend sized person). How does your bike handle that kind of weight? Is it really sluggish off the line?

 

[xander18]

xander18,

Here is an Excel spreadsheet that shows RPM vs MPH for all combinations of sprockets, gears and wheels, including MikesXS overdrive 5th gear. Just click on the yellow cells to reveal a pull down with the value you want.

XS650 Revs

Awesome! But now I want to do the overdrive 5th

 

[WacoBrian]

i know the overdrive would be purfect

 

[xander18]

i know the overdrive would be purfect

Yeah, I'm building a cafe XS (eventually) but right now I'm working on a 'long haul' XS, looking for all the right mods to do. It'll be efficiency and comfort stuff, so overdrive would be awesome.

 

[oldbiker]

hi i know its not what you asked ,,,,but a guy in victoria is now building a 6 speed set of gears to run his super modified xs650 which he,s building for a land speed record its on the yamaha xs650 club of australia.....well worth a peak at... regards oldbiker from australia ....

 

[BigJimmyW13]

And where would we get a peak at it?!

I am not sure if this is who you are talking about, but one quick google and I found this: 6 speed transmission

 

[jamesgs4]

I run a 18/30 combo, and it is still fine off the line, and great on the highway.