Warrior spitting oil

[banshee84]

My buddies warrior spits oil out of the breather hose into the airbox. It starts fine and rides fine for about 1 min. Then when you rev it high it has no power up top and gradually loses all power. I can pin the throttle but it barely revs. Eventually it dies and is hard to start. Does this mean it needs a new top end. If so how hard is it to put a new top end on a four stroke?

[86 Quad R]

remove the hose going to the breather where it hooks to the engine. while holding your finger over it start the engine. watch for smoke puffing from the lil nipple from where you removed the hose. maybe a bad case of ring blow-by, allowing crankcase oil to be pumped through the carb and into the cylinder.

[banshee84]

Yeah someone else suggested it was the rings most likely. I will try it thanks for the advice I appreciate it