Quote:

All of my Yamaha dirtbikes (one quad), '99,'01,'03,&'04, have only screen filters from the factory, and we know the dirt/wet conditions that they're put through, always at full throttle/redlined.



I am assuming that they were 2 strokers? If that is the case that is two different systems 2 strokers are either injected or premix and the only oil in the crankcase would be for the transmission, so you really can't compare the 2, that is unless they were 4 strokers.