any tips for a leak free installation of the primary case O-ring seal?

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I will stay with my belt drive over half a tube of RTV to stop a leak. LOL
Yeah, but when they shed their teeth like an 80yo at bedtime, they’re not so attractive anymore. Like Dave’s did in Mountain City. :p
 
Shimming the inner primary is a very important step that often gets overlooked. On my 73 850 I knew that it needed to be done to cure a small annoying leak just like yours. Nothing major, but it was the only place that any oil would make an unwelcome appearance. Hylomar would work for quite a while, but eventually a drop or two would crash my party. Being on the conservative side with my personal energy expenditure ( my wife calls it laziness) I didn't want to go through the major hassle of pulling off the inner primary. Something else always seems to crop up or go wrong. So I took my shim stock, fender washers of various thickness, and cut a 3/8 inch slot so that I could slide it over the mounting stud without having to remove the inner case. Got the slight warp out and kicked that bitch leak to the curb. 5,000 leak free miles including a one day 700 mile freeway blitz. I celebrated by ordering up a milled from billet primary from Matt at CNW. Motoporn!
 
Warped or damaged parts can be repaired or replaced...but trying to make an oil-tight Commando with RTV - it's easier to accept that there will be small leaks and not worry too much about it...
No try. Did.
Like Yoda. :p
 
Shimming the inner primary is a very important step that often gets overlooked. On my 73 850 I knew that it needed to be done to cure a small annoying leak just like yours. Nothing major, but it was the only place that any oil would make an unwelcome appearance. Hylomar would work for quite a while, but eventually a drop or two would crash my party. Being on the conservative side with my personal energy expenditure ( my wife calls it laziness) I didn't want to go through the major hassle of pulling off the inner primary. Something else always seems to crop up or go wrong. So I took my shim stock, fender washers of various thickness, and cut a 3/8 inch slot so that I could slide it over the mounting stud without having to remove the inner case. Got the slight warp out and kicked that bitch leak to the curb. 5,000 leak free miles including a one day 700 mile freeway blitz. I celebrated by ordering up a milled from billet primary from Matt at CNW. Motoporn!

Instead of fiddling with shims in the hope of getting it just right, I took the center bolt, chucked it into the lathe and cut more threads to make it like the MarkIII part. Now just install the inner cover, snug up the added nut so the stud fits perfectly and tighten the inner bolt. Job done.
 
Instead of fiddling with shims in the hope of getting it just right, I took the center bolt, chucked it into the lathe and cut more threads to make it like the MarkIII part. Now just install the inner cover, snug up the added nut so the stud fits perfectly and tighten the inner bolt. Job done.
i'm a bit of a novice - having a tough time visualizing exactly where this added nut goes. i'm assuming it replaces the (060399) washer shims - ???
 
Just imagine that the threaded part that bolts through the cradle has longer threads so that there can be a nut on both sides of the cradle. After the inner primary is installed, you just run down the "second" nut that is on the outside of the cradle until the piece sits snug up to the inner cover. Then tighten down the original nut on the inside of the cradle. If I could post a pic here of the modified piece I would, but no go.
 
any tips for a leak free installation of the primary case O-ring seal?

This. Run this nut down until the stud sits against the inner primary, then add the inner nut against the cradle.
 
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