Cycle oil leak

[Backally]

Lot of knowledgeable people here, looking for advice. My Yamaha has had a slow oil leak forever. It seems to be from the seam between case halves. I’ve tried rtv and other various sealants, no luck. Right now I have The right stuff in there, there is a groove there that was cleaned real good before application. Just a few drops after riding while engine is cooling. Can’t JB weld it or anything permanent in case it has to be opened up someday. Any ideas to stop this?

 

[jbc426]

In general, oil travels down and back. Oil leaks can be relatively easy to locate, but I've had two that were very hard to find the source of on both my Mopars. I ended up buying some florescent leak detection dye and a black light flashlight from Amazon.


I was surprised when the leak was not in the area I thought it was coming from. Without the tell tale luminescence leading me forward of where I was suspecting, I never would have found it unaided.

If it is found to be leaking between your cases, it will have to come apart. Then using emery cloth and a flat piece of glass. make sure both sides are dead flat. Then clean everything and reassemble using Permatex Ultra Seal. Make sure you massage it into the metal well.

Are you using a torque wrench to tighten your case bolts? Another location oil can get out is from under the bolt heads that hold the case together. You may be able to remove one at a time, check and dress any burrs, clean the face of the bottom of the bolt head and it's matching seat on the case and put a dab of sealant there. I had oil pan bolts leak at that spot until I pulled them and sealed them.

Good luck.

 

[Backally]

I used the leak detection dye. I put it in, started the bike and let it warm up without driving it so no wind blowing it around. It appears to be in that groove, glows a thin line between both sides of the sealant and aluminum case. I never took this apart, still factory assembled. Just started leaking a couple years after I had it.

 

[JBurch]

Yamaha what?? The fact that it is a vertically split case is ODD to me, Japanese generally favored horizontally split cases just for this reason. It very well may require you to pull engine and split case to fix. It generally does not work to push something in to stop a leak.

 

[Backally]

98 Yamaha xv1100 virago. It’s not bad enough that I’d pull the engine and break it down. I was just hoping there is a way to seal it without tearing it apart

 

[AJ/FormS]

Old Yamaha's are like British bikes; you gotta expect the mess; it's just a fact of life. The older the Yammy, the worse the leaks were.
Is your second gear still working?
If yes, the day will come when it will start jumping in and out, and that is the day you can strip the engine down and fix the seepage.
The sealer to use is a 3M product, that you can buy from the dealer as Yamabond. Clean it right and thatchit will seal her up for a long time.
In the meantime, put a pressure gauge on the CC and make sure it is not building up pressure.

To patch it, you can use a gas-tank sealer, called Seal-All. But you will have to clean the heck out of the area. This won't be pretty, but it is removable at a later date.

You cannot use JB because as the engine heat cycles, it shrinks and grows, and sooner or later the JB will chunk off. But long before that happens, the leak will find it's way around the delaminating JB.

Good Luck