I think you could get a little better mileage then that on a car. Check your timing & try advanceing it a little more then specs. Make sure the vacuum advance is working. Take the top off the carb & check the float level & make sure the power valve is working correctly. Remove the carb & make sure there is a psssage in the gssket for vacuum to reach the hole in the bottom of the carb. With the engine warm & running slowly turn the idle mixture in till the engine starts to slow down. Turn it back out just enough to speed it up (about 1/2 turn). With proper tune up you should increase the mileage.
