87 quadracer. drained tranny oil and refilled with synthetic gear oil. drove it for a half hour and had oil coming out breather tube on top of tranny. Now I now that i put a thicker oil than what is required by manuel. 10-30- however I do not think that I should have had oil spewing out the breather tube. Plug is dark on electrode and fouls real easy.
My fear is that the gasket in the center of the case has let go or the bearing seals on the crankshaft. Any other guess's? [img]i/expressions/face-icon-small-confused.gif[/img]

 

The crank seals are most likely going out. You need to tear down your motor and fix it before you melt your piston. The same thing happened to me. It leaned out the mixture and melted it clear down to the ring.

 

I have used synthetic oils before and they will make your clutch slip. I went to the dealer they told me never to run synthetic moter oils unless designed for a 2 stroke transmision. as for coming out of the over flow tube does the transmission have the right amout of oil? I beleave it is 900ml. but it will say on your outer clutch cover. i know that synthetic oil are thinner even if they are the same #. this will make it easer to leak out of the over flow and into the main seals.