Before you dismiss my comment, I worked as mechanic from marine thru motorcycle to John Deer. I have a college degree in Ag Science and when my instructor showed me 6 set of piston rings in 6 stages of break-in I was amazed to learn that engines are often RUINED at dealer start-up. The 5 minute idle after set-up is where the cylinders are glazed and rings never seat. Believe it or not. Then he showed me his secret. AJAX scrubbing powder, my G_D I didn't believe my eyes when he poured a half a cup into the intake of a $120,000 dollar John Deer tractor engine. Too much puttin around during build-transport-display-testdrive. Yet Yamaha told me to mark their rings on a camchain replacement and reinstall in exact location and take a straw full of AJAX and blow into the intake while on the bike stand to reset the rings. I usually do that now instead of buying new rings.
I had a volkswagen diesel that wouldn't stop running after I ran it floor boarded for ten minutes up a hill. The problem was oil build up in the valve cover that got sucked down the intake valve stem powering the diesel engine without need for diesel fuel. I had to stop it in gear. It's called a runnaway. The culprit was a head gasket that had a too small of a drain back hole punched into it that restricted the oils return to the oil pan. I have a Polaris 325cc currently that does the oil build up in the cylinder head also if I drive the shit out of it. So I put a vent tube down under the engine to prevent oil in my air intake housing. Some day (doubtful) if I ever tear it down I will address the issue.
Also ring end gaps can some times rotate around to the same spot on the piston and allow pressure to get to the crankcase. I think that is why TOTAL SEAL rings came into being and if I remember right that is why I only used TOTAL SEAL on horizontaly opposed engines cause the weight of the uncut side would over time jiggle the end gaps to the top and cause blow-by.
Last edited by Romans5.8; 12-11-2012 at 10:57 AM.
Reason: Please edit existing posts before posting again.