Richard:

The K&B Sportster 65 was made in an early version with the crankshaft running directly in the aluminum case. Pull the prop drive washer off and look at the front where the crank comes out. If you can not see a brass ring around the shaft you have the early version - go on line to MCoA and order the late style case with the bronze shaft bushing. The last one I bought was about $22, so it's not an expensive upgrade.

But some leakage around the shaft is necessary, that's how the oil gets up front to lubricate the shaft.

And as Dru said, running synthetic oil in a plain bearing engine is a fast way to destroy one. ALWAYS use a fuel with a good amount of castor oil.

And again echoing Dru, prop it up. Don't try for high rpm, again, that will shorten its life. Keep the rpm down by using a larger prop than you think it should have, try not to go too much over 10K rpm, let the torque pull your plane, not sheer horsepower.

Bill.