I have a 1987 lt80 for my son Im rebuilding the engine. What performance upgrades can I do to get some more juice out of it besides boring and larger piston

 

Welcome to the forums.
FYI: boring and big piston don't make much if any more power.
Internal mods (porting) and clutch mods to match the motor is what your looking for.
I'm sure others will chime in.

 

O'BOY here we go again. go into the kids section and search lt80. you will find more that enough reading for the day. mill head , cut rear shoes, give jack moore a call(code name LT80) and he can make your motor really nice!