leaking Primary/Engine Case

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leaking Primary/Engine Case

Post by nopdog » Tue Dec 10, 2019 1:07 pm

My 1967 441 is running very well.
Except the primary case and engine case are out of true. They do not mate together properly.
The primary case when laid on a piece of glass rocks from side to side only slightly but against the engine casing it rocks about an 1/8 inch.
Is there an easy fix to seal the cases?
Or is the only fix a complete strip down and mill the cases true.

The bike is running so good but leaks so bad from the primary case!!!

Help!! Your thoughts, ideas will be appreciated!!!


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Re: leaking Primary/Engine Case

Post by ampshire-og » Tue Dec 10, 2019 1:19 pm

I have found the rear of the crankcase to be just as bad as the primary case itself! Obviously you don't really want to strip the whole engine to machine the face of the crankcase so I just remove material from the primary case by rubbing down on a surface plate using 80 grit finishing off with 220 or so.
Generally I find evenly tightening the ten allen screws up does the trick leaving the crankcase to flex a smidge. I don't use a gasket either, I rely on a good quality instant gasket which works for me. But I have done all that only to find the high gear seal to be the culprit or the chain oiler aperture! I'm sure the guru's on here will have other fixes to be considered.

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