Need engine help please.

[96tacoma]

I am working on an 06 yfz450 and there is oil coming from the crankcase vent into the airbox only when quad is on track. No oil entering when at idle. It lost around a quart within six or so laps any ideas? the starter has been removed an installed the gytr kick start an block off plate.

[mxpimp2000]

kickstart has nothing to do with this.

depending on how fresh the piston and rings are can tell u what the problem is. if ur rings are worn it allows blow by and the compression thats blowing past the rings from poor seal pushes into the crank case blowing the oil out of the case into the black breather box on the subframe which when its full or clogged it blows into the air box.

also it can mean u have too much oil in the bike and its pushing out what it dosent need, not sure on how true that statement is but thats wat i was told one point in time when mine was blowing oil onto my filter and i figured it out once i kept ridng it and my rings were actually bad and it wore my cylinder at TDC so i had to be out a top end kit and cylinder since it was junked.

also if u are on the rev limiter it will cause it to blow oil out. i removed my black box and ran the hose from the case and from the top of the valve cover to the ground. mine will still drip oil now and then but its not because my rings are bad. i race my bike pretty hard and i keep fresh oil in the bike every race so its normal to blow a small amount. but not a quart or anywhere close