how to tell

[Ruby Soho]

this isnt on a quad engine, but it shouldnt matter. (on a drz110 if anyone wants to know)

how would i tell if a valve seal is bad? the bike smokes terribly so im redoing rings/gaskets. how do i know if the seals are shot aswell?

[woodsracer882]

After you put a new piston and rings in it and still smokes your seals are more than likely shot.

[400exrider707]

Piston rings and valve seals would all be a good thing to do. Chances are that if it's been ridden enough to be smoking it needs all of that anyways.