Not liking the comp readings. You may have a stuck ring from carbon. I would be curious to how each cylinder wall looked. May have scoring, then there's not much to do but rebuild or replace. You can use a wand light and try to see into the cylinders. I use awand camera to look inside the engine. If you want to start on your own and try a few things, replace the spark plugs, clean the carb, fresh fuel. If it runs good, then do a comp check after to see if it is any closer to even on the cylinders. One other thing to check... not sure if it has one or two carbs.... if two, check to make sure both are opening the same and all the way when the throttle is openned to wide open (do this with the engine not running). If one, make sure it is openning all the way.