Having recently rebuilt my Dommie with a new cam chain, after a few hundred miles I noticed a rattle in the timing case. Opened it up and found everything ok except the top run of the cam chain rattles against the top adjuster lock nut when flicking about (during kickstart operation).
Chain adjuster at the bottom is as high as it can go but the top run of the chain still has around 1/4" up/down play (manual says adjust to 1/8" play.). Chain is close fitting on sprockets.
Any thoughts on how to address the problem welcome. Has anyone experienced similar with new chains?
Thanks
Jon
hello Jon - You may have the…
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Howard has identified the likely cause of this problem.
The chain adjuster unit has 2 clamping plates of differing lengths and thicknesses..
First the thin plate goes on the studs with the longer end pointing downwards.
Then fit the tensioner blade and finally the thick plate with its long end upmost.
1/8" play in the chain at its tightest spot is recommended.
Don't over-tighten the reduced hex plate nuts. 12 to 15ft lbs is enough.
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Thanks Howard and Phil for…
Thanks Howard and Phil for your comments. I took the tensioner assembly apart and found it to be correctly installed as you advise. I refitted the assembly but found that if i pushed the tensioner upwards to the end of its travel, it reduced the play somewhat (to between 1/8" to 1/4"). This results in a gap of about1/8" to the top nut. It now kicks over without rattling.
I fitted the new chain straight from the packet and can only surmise the new chain maybe had some lubricant in the links giving a flse impression of the correct tension on rebuild. This has washed out in service and been replaced by oil causing slightly more play in each link.
In hindsight I think the old chain was probably fine but I had no idea of its age.
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hello Jon - You may have the outer fish plate upside down. It's very easy to check. The two holes are not symmetrically placed on the plates. The bottom plate won't stop the adjuster moving higher but the top plate will. Remove the two 5/16 inch reduced hex nuts and shakeproof washers and remove the top fish plate. Turn it the other way up and check that you can get enough movement on the adjuster to get the correct slack on the top run. Hopefully that will be the answer. It not you will need to replace the chain. Good luck, Howard