Chain length?

Hey guys,

Posted this over on the xr250 board and got nothing. :D Hoping my blue brothers can help me out :D

I'm working on my cuz's 87 xr250. Through neglect both sprockets, chain, rear wheel bearings needed replacement. Got all the parts from rocky mtn. Everything was going smoothly until I tried to put the chain on...too short. Went with the stock gearing 13,48, 520x108 chain (right out of the catalog and confirmed w/the sales guy). With the axle all the way forward it looks like it is 1 link too short..even if I could get it on it would be too tight. I counted the links on the old stretched chain and it was 108 also, although it was about 3 inches longer!

How do I figure out how long the chain needs to be? :)


Any takers? :)

If those are the stock # of teeth ftr/rr, and the stock chain is 108 links, I'd be trying to figure out wht the axle isn't going all the way forward......otherwise, wrap the chain around the rr sprocket and see how many valleys are between the ends and get a chain with that many more links.


Just went to sprocket specialists web site and 108 is correct, as are the #of teeth....looks like the axle isn't going all the way forward to me....

Hey Mike, Check to see that you dont have a 50 rear sprocket and not a 48. That would make more sense. Count the teeth to verify. :)

Sorry to ask but :

Did you double check the chain size ?

Double checked everything today. Counted teeth and links. 13, 48 and 108, yup, yup, and yup. The axle is going all the way forward in the swing arm. Slack adjusters are "snails" w/ 40 clicks on them. With two empty valleys on the rear sprocket I had about 10 clicks out to get the chain adjusted. That would leave 30 clicks for future adjustment. I'm doing all this work on a stand w/ wheel elevated although I put it on the ground to see if it made much difference and it didn't. Thanks for the help guys, I'll be getting a 110 link chain tomorrow (still curious why everyone calls for a 108 :))

Mike :D

Finally figured it out after I got the new 520 x 110 chain. It turned out to be too long! Upon close inspection the first chain that RM sent was a RK50 (stamped on side of link) which is close enough to fit on the sprockets but overall link spacing is shorter than the 520. It is also slightly wider. So, I cut two links off the new chain and fits perfect. There went about 2 hours of my life thanks rocky mtn :)


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