99 yz400 here are the sympthoms
high idle, it does not get affected by idle screw
could get it turned on like a two stroke without much effort
smells like its burning oil
after running for a while it started to puff out white smoke out of engine vent hose and afterwards it started to leak a little oil thru the same hose
other than that the bike runs fine but it smells like s**t, high idle but it doesnt semm to have a power loss (not that i would be able to tell the difference i bought it used about three weeks ago and never ridden a 400 before only 250) its just pretty fast.
so is it time to replace piston and rings or it couls be something else
after tearing it down here is what i found
piston is good
oil ring is not
oil is not milky however the is no coolant, where did it go?????
so it overheated and fried the ring but where did the coolant go