You would know if it's REALLY TIGHT by turning the crank with a wrench ...spark plugs out will ensure that you are not fighting compression as well.
did you not see post #8 and before?? You should have played with the tensioner. It's really pretty simple.... but yes,assuming you do not have the shaft lock screw tightened, if you turn the "black knob", it allows the tensioner shaft to recede..By "allows" I mean that if the tensioner is REALLY TOO TIGHT against the chain, this will relieve it. Then, Letting the black knob go, locks the forward length of the shaft....the thing is designed so the shaft slowly extends as the cam chain wears and stretches but maintains some "spring-loading" too.
Simpler is if you remove the tensioner and play with it to understand it. You can turn the knob, push the shaft in a bit, relock the shaft, and reinstall it to engine. Turn the motor to tighten the camchain at the FRONT of the engine,release camshaft lockscrew.
but before all that, if crank turns ok with a wrench by hand, and the starter bucks like a wild animal when power applied, (it should!!) the trouble is some where else
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