Motorcycle Repair: 1980 xl125 smokin like a train, leakdown test, leak down test

Question
hey i got a 1980 xl125 that has new rings but is still smokin like a 2 stroke any ideas

Answer
Josh,

-were the rings done recently and do you
know if the cylinder was worn badly or properly
honed or bored out?

-The valve guides could leak a bit of oil
but the best way to check for leaking
rings is a leak down test or at least
a compression test with and without
a bit of oil in the cylinder to see
if the rings are leaking.

-If the compression goes up alot
with a small amount of oil added that
means the rings are leaking.

-have you checked the air filter,
they can get oil soaked and cause
smoking.

-the exhaust pipe may be full of unburnt oil

-a leakdown test puts air pressure in the
cylinder and determines how much the
engine is leaking past the valves, rings
etc.

-is the gas new or old? Old gas is rank and
can burn poorly causing some smoke.
The fuel does not have oil mixed in it for some
reason?

-if the rings are really new they may take
awhile to seat or seal well.
They usually don't smoke much though,
The cylinder may need a rebore and new
piston if it is badly out of round.