Have two lt80s . Bought them both non running low compression figured I'd just do top ends an the usual seal gasket kit ect . Had rode bikes like these as a kid an thought I'd try an get them going for my kids for Christmas. Let's start with the first one it's a 96 I bought a niche top end kit head jug piston gasket set installed with no issue . Pulled carb off cleaned , put boysen reeds in it new air filter spark plug sealed the housing up an went further with new petcock fuel lines coil new battery ect . Started it up with ease idled smooth sounded great did three heat cycles an runs amazing. Putted around the yard quarter throttle mostly an a little snap here an there to get up the small incline in the yard . Done this twice since the break in not romping on it or even going past half throttle. But after riding fifteen minutes or so engine bogged down no power acting like it got hot an wanted to seize didn't make since pushed in garage an let cool . Started back up no problem idles good has power but I let it warm up an same thing . Put my bore scope in cylinder to see if there was any issue with new jug an piston can't seem to find any scoring or heat signatures that indicates problems plug was nice an black ran it rich . . Since then bought another top end an same problem. Any help would be greatly appreciated. I'm also looking for.parts for my other machine . Sorry for the long form . Thanks in advance

 

Obvious question, is the oiling system working OK? Many have had the oil injection system disconnected and owners then use a fuel oil mix, but they sometimes forget to tell the new owner when they sell the quad. I always run unknown LT80s on a small quantity of mixed, and pull the injector pipe of the carb to see if it dribbles oil when running.

Jack, the forum's LT80 expert doesn't rate the aftermarket cylinder & piston kits, reckons the cylinders all come from the same Chinese factory, whether cheap or expensive, and machining quality is poor. I have gone for genuine pistons and a rebore on the few I have done, but did try a cheap kit on a Honda 90, which worked OK.

 

China kits are no good.