I recently got a 2000 polaris Xpedition 425. After riding it I noticed gas coming from the overflow of the Carb and pressure building up in the oil tank. Enough to blow off the dipstick when I unthreaded it to check the oil. I bought a new carb and put it on, changed the oil, changed the oil filter. Took it for a spin and it's still building pressure. When the pressure builds it seems like oil is seeping out from the engine located underneath where the electric starter is mounted. Any ideas what I can check next? I'm at a loss at this point.