Valve Issue - Right? Wrong?

[PancakeShake]

78 GS 750

Started bike....smoked.

1) Compression check: 30, 90, 30, 30 (1-4)
2) Pulled engine, leak down test.
WITH CAMS IN: Fail,Pass,Fail, Fail (1-4)
WITH CAMS OUT: Pass, Pass, Pass, Pass (1-4)
3) That tells me, rings are good, valve clearance too tight.
4) Checked clearances
5) Bunch of cam lobes had ZERO clearance between the shim / cam lobe
6) Bought smaller shims to put them in spec

QUESTION: Do I need to do valve seals?

I would assume the oil is coming through them because the leak down told me my rings are alright. Also, if my valves were never quite seating, that means all the combustion pressure when the engine was running was reaching the seal, and most likely destroying them, or weakening them at the least. Right?

 

[d9canada]

You didn't mention the miles on the bike but generally just the years say enough - 30 year old valve seals are likely to fail. It's not the kiss of death to run leaky seals, but until the bike warms up, it's like a mosquito abatement system. You'll also get a fair bit of oily mist in your aircleaner from the top end breather. It's just a good idea to change old valve seals when you have the head off. Use the blue or green Nitrile or Buna N type. Check you valves' top end and dress down any sharpness on the end with a fine file. There's two steps, get the seal into place and get the valve inserted without tearing the seal.

Some guys use a valve as a guide for the seal. Slip a 3/8 drive socket of the right size to press the seal onto the head, then carefully put the seal on the end of the valve. Next, insert the valve into the guide from the top, slip the seal down, then follow with the socket and press the seal down into position. Be very careful to hold the seal in place with the socket as you gently remove the valve. Then take the "real" valve for that position in the head, insert from the combustion chamber, very gently while keeping a finger on top of the seal. The key thing is to avoid tearing the seal.

Though it's sort of 20/20 hindsight now, before you yank the stove due to surprisingly low compression, check your valve lash. But more important now, when you pull your head, check the valves and seats in case there's any sign of burning - that's a common result of running too tight a clearance. Give them a light lapping if they appear OK and you should be OK.

 

[crazypj]

GS valve clearance is only 0.001" ~0.003".
It's highly likely the exhaust valves have tightened up excessively.
If you could have gotten bike started you would probably found it ran 'fine' when hot as the alloy head expands way more than steel valve.
Your cams removed test is good as it doesn't show burned out exhaust valves (very common back in the day, did a boatload of valve changes)
It's a real good idea to set exhaust valves at 0.004"~0.005" as they will tighten up slightly when you have some clearance (just put up with the ticking for a few thousand miles )

 

[PancakeShake]

http://youtu.be/zzI2EIwZBdE

Just rebuilt it.

Here is it running. Valves tap cause I set the clearances on the high side.

Seeing that the smoke is hardly noticeable I would say I'm alright...what do ya think?