Chain Adjustment
 

On a 1988 XT600 Tenere (3AJ),

Just a quick question, I am a big guy and have the suspension set on the firm side which I like, I have no problems with the handling, but I do have problems with the chain adjustment.

I pressume you measure the chain tension with myself sat on the bike, the problem I have that with the type of adjustment on the bike the chain is either too tight or too lose, I can't set it in between because of the adjuster.

Is it better to have it tight or lose, is there something I can do about this?

Do I need to by a new chain and sprockets etc?

Any ideas greatly appreciated.

Oh and another question - I would like to make the throttle shorter, is there any way I can use a quick throttle type device, such as they use in Motocross, if so where can I find one of these?

Scott

[This message has been edited by sjbarrow (edited 15 May 2001).]

To clarify this, YOU have no effect on the chain tension whatsoever.

What matters is that the chain is never under any tension at any point in the suspension travel. Too tight can destroy the bearing behind the primary sprocket in your transmission, so you NEVER want too tight. Always err on the loose side.

The swing arm pivots from a point behind the primary sprocket, so the wheel travels a different arc than the chain. This ends up meaning that when the front sprocket is in a straight line with the swingarm pivot AND the rear axle, the chain is theoretically at it's tightest point, and this is where you set the correct chain tension. This can be tricky, so many manufacturers give instructions to set the chain under various scenarios, usually at rest on the sidestand and with x tension somewhere.

If in doubt, here's how to get it right.

Compress the suspension till all three are in line as above, then use a tiestrap or rope or something around the frame / seat and wheel to lock the wheel in place. (Easiest may be to remove the shock) Be VERY sure front sprocket, swing arm pivot and rear axle are in a straight line.

Put the bike on centerstand or a box so the rear wheel is in the air.

Then spin the rear wheel slowly, checking the chain every few inches for tension. You will discover that the tension will VARY! Chains stretch unevenly, and sprockets are often not perfectly round. Find the TIGHTEST point, then carefully adjust the chain so that you have 1" to 1.25" (25 - 30mm) slack.

What I then do is figure out an easy check with the bike back on the ground and the suspension in normal relaxed mode. Find the tightest spot in the chain, and check the slack from the chain to somewhere on the swingarm that's easy to remember, and you're done.

If you can lift the chain off the rear sprocket at the rearmost point any amount over 1/8" or 3mm the chain is probably toast, replace it asap. If unsure your dealer will show you how to tell, and also if your sprockets are bad and need replacing. ANY sign of "hooking" i.e. the sprocket teeth are not exactly the same profile on each side, they are done.

Re throttle, I don't know, but your dealer should. This should be possible. Anybody?

------------------
Grant Johnson

Share the Dream!
at: www.HorizonsUnlimited.com

Cheers for that, I will try adjusting it again, it would seem I would have to leave it on the loose side, but it seems much to slack. One notch up and the chains too tight.

I might invest in new chain and sprockets as a precaution, the sprockets are beginning to look a little worn anyway.