motor oil in air box need help?

[custom R]

I went to the country this weekend and it was running fine then it died so I got it re started and it wouldnt idle so when I got back I checked the air filter and there was motor oil in the air box and its coming from vent tube that goes to the motor and when I get it started air is blowing out of the breather like the crank case is pressureized what would be causing this ?? I have a dyna tek cdi,k&n filter dyno jet kit and a 2" exhaust tip It ran normal when I got it going but there was more oil in the air box any help would be great

[N2SAND]

Thats a common problem, when running hard the crankcase creates pressure and pushes oil out that breather hose into the air box, pretty stupid design there is a fix its called a siphon break its a little tank the oil goes into instead of the air box most places that deal with rhinos should have it or know where to get it I got mine at kms performance.

[custom R]

Its creating quite a bit of pressure just idleing or just cranking it with the starter