Hi all.
Dommi 99. I have a new, 42 link chain driving the mag with an auto advance unit, but it's touching the top of the oil pump.
I'm presuming it's quite common as I've often seen pumps for sale with what look like chain groves worn into them.
Grateful for any feedback on how to resolve it.
Alarm Bells
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Thanks Philip Tricky to…
Thanks Philip
Tricky to photograph clearly. As you can see, there is also quite a bit of wear on the engine case also.
Much of it would have been caused prior to this new chain and rebuild as the bike has well over 100K on it.
I estimate there is about 1mm clearance between the pump at the tightest point. when slack there is definitely contact.
I recall a thread once about chains with the same number of links varying in length so im wondering if this may be the case here.
I dont have any other chains to compare unfortunately and i believe this came from the noc shop.
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As Phil says should not…
As Phil says should not touch ,However the intermediate gear can (and does ) sometimes have its bush bored excentric which can give alarming variences in the cam and mag chain slack. I am experiencing this on the 650 I am working on. Chain tension varies so much that it goes from too slack ,then too tight making the motor feel hard to turn over .Looks like I am going to have to fit a new bush . This is with a new chain and a dummy cover !!.
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Jason - If you have the…
Jason - If you have the correct studs for mounting the mag to the crankcase you can adjust the chain tension. The studs are 5/16 inch but are waisted to 1/4 inch where the mag holes are situated. The nuts are a reduced hex 5/16 inch BSCycle (26 tpi) and the washers are recuced diameter 5/16 inch. There is an art to tightening the chain. Make sure that the auto advance unit is tightened to the mag armature then pinch the outer nut tight and move the mag in a rotating curve up and down, If the chain tightens enough the job's done and you can tighten all the mounting nuts and then slacken the advance unit to time the ignition. If not, then do the same procedure with the inner nut tightened first and if that also fails try the upper nut first u.s.w. In one combination you will get it right........eventually. Good luck, Howard
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Something very wrong here. Can you post a photo of all the parts in place. The diagram shows them well apart from each other but is a bit misleading. The reality should be around 3mm gap between the chain and pump.