My son has a 92 ds80 and it leaks oil out the exhaust from engine all the way back what could cause this?

just had new seals put on by repair shop then this happened so don't want to take back. Don't trust them anymore just want to try and fix it so son can ride thanks.My son has a 92 ds80 and it leaks oil out the exhaust from engine all the way back what could cause this?
piston rings are bad


valve bushings need replacing


Basically it needs to be rebuiltMy son has a 92 ds80 and it leaks oil out the exhaust from engine all the way back what could cause this?
I assume the oil ratio is correct.


A little oil is normal,


A lot of oil/smoke is rings are worn out/ not seating correctly,


Just ride it and deal with it, its an older trailbike. no damage is being done.
if 2 stroke engine make sure u have correct mixture or if autolube get pump settings adjusted if 4 stroke [worn piston rings] blue smoke
2 strokes always blow oil out of the exhaust. Sounds normal to me.

poison ivy