Motorcycle Repair: yamaha 500 TT engine repair, check oil level, crankcase oil

Question
Hi I have a 1977 yamaha 500 TT , the problem I'm having is that when I go to kick start my bike it blows oil back up through the crankcase oil breather. The bike has good compression and I've checked for a burnt piston, colapsed rings,etc. could it be a stuck oil pressure relife valve or what? My repair manual dosent seem to cover anything about this kind of problem. Any help would be greatly appreaciated  thanks.

Answer
Hi Terry,

Check oil level for proper level first. When over-filled, blow-by gasses pressurize the space above oil in the crankcase and forces oil out through the vent tube.

If the level is okay, advise. We can go from there.

Remember to include your email address as requested. I return tech information files by email.

Respectfully,
Mark Shively