Leaking manual petcock is driving me crazy

michaelpthompson

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OK, so my left petcock was leaking when I got the bike. 75 XS650B, manual (on/off) petcock, NOT VACUUM. Got a rebuild kit from Mikes XS, took it apart, polished every surface, put in all the new gaskets, put it back together, still leaking. One thing that got my attention is that the gasket on the back side from the kit was much thinner than the original, so I put the original back in. Still leaks. Decided to go old school and Permatexed it. Still leaks. Can't see exactly where it's coming from. It's on the back, not the outlet tube, not the on/off/res handle, and doesn't seem to be coming from where it bolts on to the tank. Can't tell for sure, but I didn't feel any fluid there when it put my finger on it. So it really seems to be coming from the plate on the back as far as I can tell, but with a new gasket, old gasket, Permatex, whatever, how can it still be leaking? I'll probably order a replacement from Mikes, but would love to have this solved in a shorter time frame.

Any advice or sympathy appreciated.
 
Sounds like angus67's idea should work but if not, you might want to try a Yamaha parts dealer.

Both of mine on my 77D were leaking and after reading of so many failures with parts from Mikes/XS650Direct here in Canada, I found I could still get the OEM parts from an approved Yamaha parts dealer.

Cost more, but, Yamaha parts and no leaks.
 
They may be. I don't have them on me right now as I am out and aboot. But they have the triangle bases as opposed to the oval shape. I can measure when I get home. They were from xs650 direct brand new. Will give you a Good deal, if they work for you
 
I put some talc in my hand then blow it on.
This was not a subtle leak, no question where it was coming from. Just pouring out the back side of the petcock. Permatexed the whole thing again, let it dry, still leaked like a sieve, so I replaced it. No more leak. Now I'm just having trouble getting the tank back on. Doesn't want to slide like it did last time.
 
This was not a subtle leak, no question where it was coming from. Just pouring out the back side of the petcock. Permatexed the whole thing again, let it dry, still leaked like a sieve, so I replaced it. No more leak. Now I'm just having trouble getting the tank back on. Doesn't want to slide like it did last time.
I had that same problem with the tank last time I put it on as well. I banged mine right against the post and took a nice chip out of the tank. Could lube up the rubber bits underneath the tank I suspect. I would also put a cloth or a rag between the post and the very top of the tank so it doesn't slam into place and chip the paint like mine did
 
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