I just bought an 05 BF 750. Only 20 hours on it, bone stock except 26" 589s on c series wheels. I have noticed that when I ride long tall wheelies or drag the rear rack the oil light will blink on and off and it smokes a little, till I set it back down. In a few seconds it will clear up. Anyone know how to prevent this, besides stop riding wheelies?

 

You already had the answer but you don't like it.
The oil is going into the air box via breather tube and burning it. The real damage occurs when the oil pump sucks in air instead of oil because all the oil is now in the back of the crankcase when doing wheelies. The oil light is bliking momentarily because there is NO OIL PRESSURE. You are risking top end damages and rod bearing failures due to lack of lubrication.

 

Thanks for the advice. I would like to put a clutch kit in it but not sure what i need for the 26" tires.