[JAM614]

I just picked up a decent XR100 (1990). Runs and rides very well but it has a noise in the lower end. Not a knock, sounds like timing chain out of adjustment. Is this a common problem and is it easy to adjust/replace? I need to get a manual. I'm a believer in you guys riding and racing these things now. I'm reliving my childhood ripping around and leaving my neighbors scratching their heads.
Any of you guys ride after racing at Louden? Considering bringing it to play on after racing, somewhere up near Frontierland during the Vintage Celebration weekend.

Can't wait for Monday!

Jeff


Jeff

 

[jbranson]

Last one I heard that made that sound had a worn out cam chain tensioner.
JohnnyB

 

[joe c]

probably the tensioner. they are about 80 bucks. get a chain while youre at it. there is a a little plate behind the left sidecover where the crank is. you can pull the chain through there to replace it. (you dont have to split the cases but youll have to pull the cam. (easy) the tensioner is a system of little weak springs and bent sheet metal and plastic. it may just need to be adjusted. i have a feeling no one ever adjusts them. congrats! ill have mine up at the fim race. maybe we should get an unofficial race going on sunday night. i was out riding mine yesterday for about an hour. too fun.



jc

aaron sent my wheel!

 

[joe c]

also, the thumpertalk.com board is awesome. the guys on there know thier shit. we asked them a million questions when we were working on ours.

jc

aaron sent my wheel!

 

[JAM614]

Great info. Thanks. Chances are that the chain and tensioner needs to be replaced because the previous owner said it was like that when they got it. Lord knows how many hours were logged on it in this condition. Thumpertalk.com, got it.
Yeah, Sunday night gudge matches!

Jeff

Jeff

 

[racerchris46]

Joe and I replaced my cam chain because of the noise. He is right about the little plate but you can probably leave the cam in place if only the chain is shot. The cam sprocket is bolted to the left side of the cam, and would come right off once unbolted. You'll have to take the alternator off (special tool-same as RS125 if you have one) to get to Joe's magic plate (thank you Thumpertalk gods). Put some strong string or safety wire on the chain before you pull it down and out the hole under the cover. You kind of have to angle it sideways to get it out. Slip the new chain back through and reattach the cam sprocket, adjust valves (probably also never done in its poor life) and try it.

There is an adjuster at the head. The lock plate is held down with a 6mm bolt, and then the adjuster is sloted. It moves the top end of the tensioner around on an eccentric. There is also another bolt on the rear of the cylinder-that is the lock bolt that when released will allow a small, weak spring to pull on the bottom of the tensioner up, making the curve in the tensioner more pronounced. Try those two before replacing the chain, but if that doesn't help,the chain will. My old chain was visibly longer than the new one. And my old tensioner had about half an inch less bend in it. I have pictures but no where to post them. Drop me mail at [email protected] and I will send them to you so you can see the magic hole.

And no jokes about Joe's magic hole.

Please.

 

[joe c]

my magic hole is awesome dude. chris, if you send me pics, ill post em.

oh yeah, chris' photographic memory is right. i can never remember that stuff. damned thc!

jc

"tex, if your bikes a cheater, its not a very good one"

Edited by - joe c on Apr 26 2007 11:03:39 PM