Hello, I just picked up an 80 Honda Express. It starts and runs ok but I notice a slight sputter with the throttle and no power up hills. I cant get it to go over 20 miles an hour on the flat. Carb rebuilds and pistons I can handle, what Im worried about is the transmission. How would I know if it was bad? can anyone tell me the things to look for and how to prioritize? I would be grateful for any advice. Thank you.