Mk3 Primary

Mart UK

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My transmission shaft was not centered in the inner primary and had been a source of an oil leak. It had run that way so long (maybe from new) that when I removed the seal it was permanently offset by 1/8'". I loosened everything up and found enough wiggle room to center it up but became frustrated trying to keep it that way as I tightened things up. So I turned a little jig out of some PVC fittings, inside bore the dia of the gear shaft and outside dia the size of the inner primary hole. That held all in place while I tightened it all up.
The stud you refer to is the chaincase steady and needs to be tightened up when every thing else is tight as to not push or pull but just support the inner primary.
Thought it over. The clutch plates are pretty much dry, just a minor trace of oil on the innermost, nearest that gearbox shaft seal. I didn't sense the clutch slipping, once I had the cable adjusted (at the handlebar lever). So, I think I will leave this alone and just focus on getting what I've done so far back together and working as it should. But, please shout if you think that's a mistake.
 

L.A.B.

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Thought it over. The clutch plates are pretty much dry, just a minor trace of oil on the innermost, nearest that gearbox shaft seal. I didn't sense the clutch slipping, once I had the cable adjusted (at the handlebar lever). So, I think I will leave this alone and just focus on getting what I've done so far back together and working as it should. But, please shout if you think that's a mistake.

If the clutch isn't slipping or dragging then there's nothing to worry about.
There will usually be some oil in the clutch assembly and the clutch bearing '10' requires lubrication.
 
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The Mk3 gasket alone should seal the joint. I normally grease the gasket as it is often reusable but if the joint face is damaged then sealant could be required but perhaps only apply it to the inner case side of the gasket and grease on the outside.

The problem area as you said is the lower screw hole where the joint face of the inner case is thinner and where oil could leak along the screw thread which might require sealant on the thread.
I've got one of these and it seals quite well:


It's reusable, sort of. Since it has to be applied perfectly dry there's nothing to hold it in place. It's not too difficult when brand new but on the re-use it's slightly stretched and has lost any cling that helps on the first use. Since it's expensive and marketed as reusable I was determined to reuse it and was ultimately successful. This is not an endorsement as such but it does seal completely without any sealant. Surfaces MUST be completely clean and dry.
 

Mart UK

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All done.

Thank you for your advice and answering my questions.

Bike currently starts first time. Clutch adjustment was a voyage of discovery. Now understand. Clutch pull is now 2 fingers. Whether due to the correct adjustment, a general clean up, or the new clutch hub, IDK. But easier pull, easier to find neutral and no slip, so far.

The pistons on the chain tensioners needed a bit of fettling to glide smoothly. Now working. The old sprag (14T) was noticeably sloppier than the new one. The old primary chain was about 5mm + longer than the new one I used grease on the primary gasket faces. No leak after the first ride (10 miles). Would be lovely if that proves to be a fix.

Really grateful for the help. Tyres replaced tomorrow, transmission oil Thursday, then longer ride on Friday. ;-)

Martin
 
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