Chain Slack

I had a good mechanic comment that my chain was too tight this weekend. I adjust it for 1" of slack, and the chain can move up and down 1". He says that it should be LOOSE for 1", not just movable for 1". I thought I knew what I was doing, but now I'm confused. If I run it looser it rattles. If I understand the CRF right, the tightest point for the chain is with the rear wheel fully extended on the stand. If that is correct, then I can't see what I'm hurting.

I believe that the chain is tightest when the swingarm is parallel (give or take a little) to the ground. 1" of slack on the stand should be ok but I would not go any tighter than that. The best way to adjust your chain is to unbolt the shock from the linkage and raise the rear tire untill the chain is at its tightest point (I use a floor jack so I can make adjustments while the rear tire is suspended). Once you have found the tightest spot adjust the axle so that you have a small amount of play in the chain. Then bolt the shock back up and measure the play. Now you will know exactly how to ajust it in the future.

That mechanic doesnt know the CRF as intimately as we do! This bike goes against the usuall chain tightening procedures everyone is used to. It is because at full extension, the lower chain roller is pushing up on the chain taking the slack out to prevent derailing of the chain while your in the air!


I think you have your bike figured out. I cant run the same slack on my crf250 that I ran on my cr 250 or it slaps the swing arm (all the time) Look at the picture in your owners manual. I use that and yea its a little tighter than what I think it should be but its within spec's and Ive yet to see any prob's. Besides untill you change the stock chain if (you have not yet) one good T-top landing, even with an inch gap, and its time to adjust the chain all over again. Ive yet to see any prob's with my sprokets utilizing the setting giving by the manual and due to the differance I check for it all the time. Let me know if find out anything better to go by.

The stock chain is sitting in a box with the stock chains from the YZ and RM, none have ever been used. I have a DID X-Ring chain, and it seldom needs to be adjusted. I have gone through one set of sprockets in 40 hrs of MX, but they probably had a few more hours to go. I have Ironman front and back now, so I don't expect to change the sprockets again for a long while. FWIW, everyone who saw the rear Ironman this weekend thought it was the trickest looking sprocket they had ever seen.

I just follow the procedure in the owners manual. When I first got the bike before it was even ridden I adjusted the chain (as per the manual) then I used a triangle file to put a "V" notch on the shock guard/mud flap at the properly adjusted position. This serves as a very handy guage so no ruler is needed to check chain tension. Just lift the chain if it goes higher than the notch adjust it if not then ride on.

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