I have an regular 80cc motor on a beach cruiser with 26x2.125 tires. The chain touches the tires slightly. I know I could use a smaller tire, but the beach cruiser looks ridiculous with thin 26x1.75 tires. I've already moved the wheel sprocket as far out as possible without causing the chain to jump off. If I remove the motor sprocket, is it possible to put a 3 or 4 mm shim behind it so that the sprocket is far enough out to avoid touching the tire?