Exhaust valve stem seal seems to be popping off

[Tim]

Backstory

Complete rebuild of my SR500 engine. New 90mm 540cc piston kit and new seals/gaskets.

Had the bore/hone and head work done by just about the best most reputable shop in Toronto. He's done all my engine machine work. He freshened up the head, grinding the valves etc. and installing the new stem seals. He checks everything and does whatever is needed. He has re-done valve guides for me in the past as needed.

Assembled the engine, fired right up no problems.

Then it starts puking oil out the exhaust. Running fine, but spraying oil out the pipe. Load the bike up in the trailer and head to Alabama.

19 hours later arrive at Kiley's Thursday. Set up at Barber, then that night we pull the engine and take the rocker cover off. Sure enough, the exhaust stem seal seems not seated properly. It's not riding on the valve stem, but it's not all the way down on the guide.

Manage to get the springs off, replace the seals (both intake and exhaust) and put the engine back together. Fires right up and not puking oil any longer. Ride it like that for the weekend with no further related problems.

Back in Toronto, take the bike out and it starts smoking / puking oil again.

I'm tearing the bike down for the winter and will take the head off and back to the machine shop to have it checked out. Any typical cause of this sort of thing? Never had this problem before.

 

[irk miller]

The peeps need a pic for reference- dramatic effect.

 

[MR915]

Todd Henning had a problem with the inner valve spring hitting the seal and pulling it off but that was a Kibblewhite conversion kit for the 450. If the seal is non OEM maybe there is a problem

 

[hillsy]

Sounds like there's a compatibility issue with the guide and the seal.


Also, some of the seals are pretty hard to get on. I'm not sure if you can adequately seat a seal with the valve still in place (we used to use a 10mm socket to "press" the seals in place when I worked in the shop - valve had to be out to do this).

 

[motorguy]

There is an amount the seal has to expand to grab and stay on.I would suggest when its apart to check that.Also spring to seal clearance should be checked and whatever keeps the valve spring centered in the spring pocket and off the seal.Make sure the guide isnt worn out and cooking the seal.

 

[Tim]

Ignore this thread. It was me being dumb.

Broke the engine down - expansion ring on the piston must have gotten overlapped and broke. Oil passing the rings. I really, really didn't think it was burning oil.

May have been a few things - for all I know the cam was also a tooth off, as I have minor impact between valve and piston (valves not bent or damaged - already been to the machine shop and back).