suzuki lt 80?

hi iv bought a lt 80 of a mate he told me he thought the cluth was broke as it just lost power for no apparrant reason so i changed it and it still had very little power to pull away so i cheaked the barrol it was worn with the piston so got rebored with prox piston kit still did not solve problem this bike just got me beat anyone have any ideas be much appreciated thanks forgot 2 mension the wiring harness was all melted together soi changed that 2