I WAS ON THE SAME BOAT AT YOU MAN! i KEPT GETTING THAT OIL IN TO THE MOTOR, i SPLIT THE CASE LIKE 3X, i CONTACTED MP RACING AND SAID THE SAME THING YOU TOLD ME. THEY SAID IN HIGHER HP MOTORS, THE STOCK 7 BALL CLUTCH SIDE CRANK BEARING EVENTUALY FAILS, DUE TO THE EXTREME SIDE LOAD CAUSED BY THE HELICAL GEARS THAT DRIVE THE CLUTCH. THEN THE CRANK WILL MOVE UP AND DOWN LETTING SOME GEAR OIL TO FALL IN. WHEN i SPLIT MY CASE, I FOUND METAL PIECES AT THE BOTTOM OF THE CASE WHICH I BELIEVE WERE FROM THE BEARING, THE TZ CRANK BEARING FROM THE TZ 250 STREET BIKE ARE 12 ROLLERS AND ARE 4X STRONGER THAN THE STOCK ONE. I BOUGHT ONE FROM MP RACING. PRICEY BUT WELL WORTH IT!
SORRY ABOUT ALL THE CAPS, HOPE THIS HELP, ANY QUESTIONS LET ME KNOW!
DRAGG-ON!
IVE GOT PICS OF THESE BEARINGS IF YOU WISH TO SEE ONE, JUST GIVE ME YOUR E-MAIL