Hello

[chronoman]

I have a GS450 1987 30K miles, that I bought in Nov last year. the rings supposedly have been replaced at 25K. Anyway the bike smokes out of the left exhaust at Idle when hot. Compression seems to be good 150 and 145. I think my exhaust valve seal might be leaking, is it possible to replace the valve seals on this type bike with out removing the head? BTW the plugs look great, a nice brownish color not a hint of oil.

Thanks Claude

[Nessism]

Are you sure the smoke is oil smoke and not gas? A leaking valve seal won't lead to smoke at idle, it will smoke when decelerating because high vacume in the engine sucks oil down the guide.

Changing the seals with the head on is possible but difficult. You need to keep the valve from opening and then depress the valve spring to remove the keepers. Compressed air in the cylinder will work and I've read where some people stuff a long rope in the cylinder through the spark plug hole. Depressing the valve is another matter - no suggestions.

Good luck.

[chronoman]

Yes its oil, had carbs rebuilt and still smokes, My theory is that on the exhaust cycle there is a vacuum created on the exhaust valve and maybe drawing oil down through the seal and guide. Keeping the valve from falling in I could use air pressure or stuff a rope down the cylinder(old mechanics trick).
Claude

[Nessism]

If you have that much oil leaking through the guide the guide/valve is worn as well. Sounds like time to pull the head and check things properly.