Motorcycle Repair: oil fouled plug, rear cylinder, pin clip

Question
my panshovel's rear cylinder is full of oil! new rings, new valves and guides . can crankcase pressure cause this ? oil is heaviest on and in intake side. front cylinder shows no sign of problem.

Answer
Your going to have to pull the head and rotate the piston till you can see the cylinder. I wouls suspect that you had a wrist pin clip come out, which cut a groove in the cylinder.
The only other place you can get oil is by the valve guide.
Let me know if this helps
Mike