Cam Chain Tensioner


650 Custom Chop
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Bendigo victoria australia
So I’m trying to tension my cam chain on a rebuilt engine and I’m very much a rookie. When I turn the engine over with the kick starter the tensioner shaft stays inside the adjuster. When I turn it over using a shifter on the rotor the middle tensioner shaft pops out almost half an inch. Why would turning the engine over with the kick starter not affect that tension Rod when turning the rotor makes it move? This is my first ever engine rebuild, I’m nearly 70 and very much a rookie. The bike has run since the rebuild but it ran rough. I took the new VM34 carbs off and cleaned and reassembled plus leaned them out a bit. Now I’m going through the cam chain tension, valve clearances and timing again step by step before trying to start her up again. Any advice appreciated. Thanks, D
Perhaps you're just not noticing it when using the kick starter. You need to turn it over slowly by hand counter clockwise at the rotor and watch the rod come out of the adjuster, or not, and adjust it until flush. I believe there are some good videos on YouTube on this, plus the tech area of the forum was the ultimate guide for me when I did this for the first time. Really good lighting helps too for sure.
The easiest and, in my opinion, the best way to check or set the cam chain tension is to do so while the engine sits there idling. You want to adjust it so the rod moves in and out a small amount, maybe a MM or so. More than that and the chain is too loose, no in-out movement means the chain is too tight. So, crank the adjuster in until the rod stops or almost stops moving, then back it off until you get that desired MM or so of in-out movement.
Thanks guys - after a frustrating day in the shed it’s JD time in Australia right now - but I’ll have another crack at it in the morning - she won’t idle yet as I was planning on tensioning that cam chain as the first step before valve gaps and then timing. Fingers crossed for tomorrow! Thanks, D
Sounds like you may be turning the crankshaft the wrong way when using a spanner. That would make the AFT chain run tight, while using the kickstarter or running the engine will make the front chain run tight
Now that makes sense Arctic! It might even explain why my timing marks aren’t lining up too - they’re only about 20 degrees out now after being 180 degrees out before - so I’ll re-tension the cam chain with your suggestion in mind and see what happens. Thanks, D