why is this happening

[blackwidow450r]

i have just recently rebuilt my 450r motor because i pushed the shifter rod through the bottom of the motor. I put all new bearings and seals through the hole motor, and new rings with the stock piston. Now the motor is pushing oil out of the transmission breather hose. I was originally told it could be a damaged oil ring. so i changed it and it still does it. If anybody out there knows why this could be happening please tell me!!

[MadMax27]

I had this problem on an atc 90, turned out it was just overfilled with oil. If thats not it your obvisouly getting pressure in their somehow, Im not familiar with a 450's internals....Sorry