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Terracite 11-17-2011 12:03 AM

Magneto install, no cam endplay?

Putting new hunt magneto on brandy new evo. Before opening the gear case, I was curious as to what the factory end play on the cam was. I couldn't get a feeler between cam and thrust washer at the back. Smallest feeler I've got is .0015 . So, I naturally assume I'm the problem, and it'll be obvious once the gear chest is open.

Gear cover came off no prob., all seems well, there are no shims on the outboard end of the cam, and new mag cover goes on with some tightness on cam bushing, but torques up ok with the old gasket on.

End play is still 0, or really close to it.

What now? Is there some way to make sure the cam is snug against the cover?

F.St.M. 11-17-2011 05:40 AM

Re: Magneto install, no cam endplay?

The newer HD cams are longer and use no end play shims. End play is non adjustable from the factory, but there needs to be some end play.

There should only be a round thrust plate on the inboard end.

Could be that your remaining 2 hydraulic tappets are side loading the cam and preventing you from being able to move it and measure the end play.

Or, it could be that your brand new cam & cam bushing have no slop at all and the oil film is creating "stiction" also preventing movement.

Try measuring again after removing all tappets and with a dry cam & bushing. I'll bet you have some play.

You will have to cram your hand down into the tappet block hole and actually push the cam outward sometimes, to get a reading at the inboard end, as the cover installation process will naturally push the cam all the way in.

Good luck.

pan620 11-17-2011 06:47 AM

Re: Magneto install, no cam endplay?

What FStM said, you still have pressure on the cam with the rear push rods still in the motor or are they adjustable and loose?

Terracite 11-17-2011 05:50 PM

Re: Magneto install, no cam endplay?

Much appreciation guys.

Solid pushrods, so I was thinking the other top had to go. While turning the engine to TDC for the rear, I pulled the cam gear towards me. Check endplay again and the .0015 went, and .003 would just kinda catch. If that's the way the factory does it now, so be it. The engine still spins easy by hand.

When taking off the nose again, that cam was TIGHT! Came close to pulling it out with the cover.

F St.M and Pan thanks!


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