Sounds like you at least need rings. When you pull the motor apart, take it to a shop and get them to measure the cylinder. They can tell you if it needs to be bored. If the cyl is in spec, measure the piston to see if it is out of round or worn. It piston measures good, then all you need is rings.
Trikes: Cagiva 200, 85? Tiger 250,(2)84 200x's , (3)86 200x's, 87 200x, (5)85 350x's, (2)86 350x's, (2)85 250r's, 86 Tecate, (3) 85 250sx's Restoring: 83 200x, 86 250sx. Too many utility trikes to list.