82 XJ650 Cam chain issues

Hello.

I have a 82 xj650 with 17000 miles, When I was checking valve clearance I noticed chain marks on the valve cover, and when turning the engine the chain will get loose where I can lift the chain between the cam sprockets and then get tight again.

It is an automatic tensioner, I've took it apart and cleaned it and nothing appears broke.

 

There is a way to set cam chain tension I believe and I've never seen a good write up other than scans of the service manual which is not easy to follow IMO.

 

Try setting the crank timing mark to TDC and check if the camshaft timing marks are lining up correctly. Is the plunger extending fully on your automatic tensioner, any burrs on the plunger preventing full extension?

 

Sounds like a worn chain to me or at 17000 it sat for some time.
Replace the chain is my advice

 

When you removed the automatic tensioner, was the ratchet pawl working? As in, it only extends under spring pressure. You can't push it back in without lifting the ratchet pawl. If it was springy like a pogo stick, it wasn't working.

Re-installation requires the end plug to be removed so the spring is relaxed.

 

Timing marks line up, and the plunger fully extends and locks. I also tried to install with it fully extended to see how much of a gap there is between the tensioner and engine, there is about 10-12mm.

After doing some more research I came across the guide bolt (bolt and jam nut under cam chain tensioner). Mine was about two turns past contact, Ive since reset it to 1/4 turn out from contact.

 

Oh the guide must have been binding so not moving towards the chain hence the slack in your cam chain. That's why the tensioner is not touching the cylinder barrels. I have seen a guide not installed properly that was not central viewed through the tensioner opening that was causing an issue. The bolt and nut you reset can stop the guide being pushed against the chain correctly if too tight so hopefully that will solve the issue on your machine.

 

The chain did tighten up more, still have a little slop but not as severe.

Dose not surprise me that bolt was off, considering all the other things I've found that previous owners did.
( 20 amp fuses in everything, 10k plug caps with 5k plugs, rounded screws and jets on carbs, missing float needle seat washer)

 

Yes better checking everything.