primary case felt seal - virgin territory, over thinking, and brain farts...

jbruney said:

As old as mine is it has yet to discover it can leak from this spot

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The only motorcycle in my garage that doesn’t leak from the primary is my 2007 XL1200R. Oh the ‘69 750S doesn’t. Haven’t put oil in it yet.

O-rings, gaskets, etc., all done about 350mi. ago when clutch/sprocket done, but didn't leak at that spot then either. Everyplace else on primary seeped though.... Now all gone for a while at least.
Pushrod tunnel is my curse. I hope you get it Joe.

it is not the total bike weight BUT the large amount of weight over hung on the mainshaft that is the issue. the belt drive can remove 2/3s of the weight in the clutch assembly and IMHO that is well worth the cost. the other advantage is you can overdrive the primary which is another good thing to do for the gearbox.

illf8ed said:

but others complain about the weight.

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well i'll be....

fab'd a new O-ring using 5.5mm silicone stock (https://www.mcmaster.com/1187n19) - installed with red rubber brake caliper grease. short 7 mile run, and checked the bottom of the primary - ZERO LEAK! can't believe it was the O-ring and/or a combination of the O-ring and standard automotive grease all along. anyway, looks like I may have finally fixed the thing. got it sitting on a fresh piece of cardboard - we'll see if I get any "spotting" overnight. happy camper -

joe czech said:

well i'll be....

fab'd a new O-ring using 5.5mm silicone stock (https://www.mcmaster.com/1187n19) - installed with red rubber brake caliper grease. short 7 mile run, and checked the bottom of the primary - ZERO LEAK! can't believe it was the O-ring and/or a combination of the O-ring and standard automotive grease all along. anyway, looks like I may have finally fixed the thing. got it sitting on a fresh piece of cardboard - we'll see if I get any "spotting" overnight. happy camper -

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Good luck. I also used the red rubber brake grease along with the seal and small screws to hold it in place. Mine doesn't spot oil overnight but when I look up under the backside of the primary there is transmission fluid, I haven't take a real long ride since I did all this work but I assume in time this will turn into a drip or drips. I'm wondering if it might be coming out through the engine bolts though I'm sure that I used plumber's tape on those bolts. I really dislike oil leaks.

it's been four or five days, and no leaks from the primary. I did have one overnight drip from the sump filter, but installed a new copper crush gasket/washer AND a light coat of brake caliper grease, and it seems to have fixed that issue (BTW, torqued the nut to 35 ft-lbs). i did order up some 30mm dowty seals off fleabay, but haven't received them just yet. the brake caliper grease on seals and gaskets is a new one on me - honestly, never gave it a thought, but it seems far better than plain old automotive grease. a big thanks to whoever posted that. it took awhile, but right now, i'm leak free - . how long that lasts is anybody guess, but i'll just take it one day at a time.

English bikes are very creative, so just give it a little time.

jbruney said:

English bikes are very creative, so just give it a little time.

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i agree - having a classic British bike that's leak free, is somewhat of an oxymoron. still, enjoying the moment....