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After finally having my 1994 project under its own power for more than a few miles I'm starting to notice a few teething issues, one of which was a primary leak. At first I thought it was the 1/8" NPT pipe drain plug, so I put some teflon tape around it. The next ride to warm up the fluid showed me that wasn't the solution, so I ordered another primary gasket. Installed that and STILL leaking with no reduction in leak volume.
Racking my brain and Googling the hell out of it I remembered one of the inner primary bolts was actually completely submerged under the level of primary fluid. See the bolt highlighted below:
Coincidentally that bolt doesn't bottom out into a casting, there's just air so nothing's stopping oil from working its way around the head of the bolt and around the threads. When the bike is on the kick stand it runs down the primary and drips right where the damn drain plug is! So far the fix has been some RTV under the head of the bolt on both sides of the washer, after I cleaned it with plenty of carb cleaner to get all the oils off.
According to the Ronnie's Fiche, that bolt didn't grow into the inner primary until 1993.
It sounds as if this is leak is happening while the engine running, but the bike is stationary? Does it also leak while parked and switched off - left alone overnight? If it is dry overnight then something else is going on. When the engine is running, the primary including clutch are spinning at engine speed, so there is an oil storm going on inside the chain-case. Hence your oil could be coming from anywhere around the primary, such as one of the oil seals.
No. The bolt is submerged in the ATF, meaning regardless of the bike's status the ATF will migrate out of the primary through that bolt passage. I put the RTV in there, and stopped the leak. My post is to raise awareness of the issue.
When I pulled the inner primary cover off my bike last summer, the shop manual said to RTV the transmission to primary mating surfaces and the 3 primary to transmission bolt holes. It also said to hit the bolt threads on 6 of the bolts. At first I thought it was kind of odd that you'd RTV the bolt holes, but I figured there was a reason for it, so I did it. Sealed up great, haven't had any leaks.
Must be a small amount of fluid gets around the threads.
I asked my self if it was designed to leak. But my instinct automatically excluded the theory.
Then I asked my self the other question. Why not permanetly plug it with jb weld or with a plug screw?
Alsi asked my self if I should replace the drain plug wirg a lever actuated npt drain plug. Never thiugh of this till Matt brought it up
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Primary leak FYI
