Centring the flywheel

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Farmerboy

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Have a question guys. How important is it to exactly centre the flywheel in the case? What if it’s a bit off centre (although though to measure precisely). This is 372xp
 
You want it centered. Perfect

A member here, Pioneerguy600, has a great method.

Put a little valve lapping compound on the inside of flywheel /crank. Slowly lap by turning the flywheel, to lap the surfaces. Clean up very well, lapping compound is abrasive. Fit will be perfect.

PG600 will chime in if I'm wrong.

The crank actually centers flywheel.
 
Yes, centre the crank left / right. It does turn freely, but am wondering if it needed to be centred exact
 
Once the case is assembled then center the crank in the case. This can bow the crank weights a tad, I put the rod at bdc and use a cold chisel to put the weights even again. Just a light shot will do it .
I’d the crank is tight in the case after assemble after you centered it try this method.

It works on the older husky dirtbikes too.
 
Once the case is assembled then center the crank in the case. This can bow the crank weights a tad, I put the rod at bdc and use a cold chisel to put the weights even again. Just a light shot will do it .
I’d the crank is tight in the case after assemble after you centered it try this method.

It works on the older husky dirtbikes too.
I put a bolt that is lightly wedged and centered between the counterweights.
Some cranks can get bent easier than you'd think.
Then you've got a wobble that eats the bearing pockets at 13,000 RPM until the bearings are loose in the case. NO BUENO..
Happens a lot to K760's on the clutch side, from other tools being thrown into the truck on top of the saw at "Miller Time".
 
Sorry if I’ve not been clear. It’s the counterweights that aren’t centred in the case. Haven’t been able to move with a mallet.
 
Yep that wasn't clear in the first post as you were asking about the flywheel not the crankshaft. It's generally best if the counter weights are close to centered in the assembled cases. However......the piston centers the con rod on the big end bearing......this figure varies wildly depending on the performance level of the stock saw. I other words the amount slop between the top of the con rod and the wristpin bosses affects how the entire lower end is established. Generally the lower performance saws have a large amount of play between the side of the upper con rod and the piston boss which means the rod can move left and right a lot........as performance increases this measurement will decrease. The difference I'm describing is like from 0.010 on a good performing saw to up to 0.200 on a cheap low power saw. What I'm coming to is.....the more high performance your saw the closer to center your crank should be so that the lower end of the con rod is not rubbing on the sides of the counter weights........and again this is controlled by the piston.....and the piston only...
 
A different question for you guys. Got this aftermarket cylinder / piston on my 372. Now as the pic shows, the ring (and pin) drops below the top level of the intake. I’m assuming this is unacceptable? Squish is at .036


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