I was given this guy by my neighbor. Said he used it around 6-7 times then parked it and got a tractor. It has sat outside in the rain for at least 2 years. It was full of water. I got it unfrozen,piston travels and both valves move. Not sure if there is anymore water under the piston. Piston walls do not appear to have any scoring but there is rust from all the water. Carb and tank have been cleaned and oil drained. At this point what should I do? Thanks for any help.