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ok. yes I replaced the gaskets in the caps. will do.

I picked up a 1990 Yamaha Moto 4 350 from a buddy in the past two weeks. Still runs very well and is the first ATV I’ve ever owned. It is a nice utility ATV that my kids can have fun on. Wondering if anyone has an owners and service manual for this ATV. I’m a DIY guy that wants to go through and maintain the ATV. I just gave it a updated paint job (photo attached). Thanks for the help.

Thanks for the help Frank!

I have in the past put the piston in a pot of boiling water for a few minutes, taken it out and repeated the steps. Then soak it in penetrating oil. The heat and cooling makes the metal expand and contract loosening the rings. You can use a small torch but be careful not to keep the flame to close for to long.

Oil the sh** out of the piston and rings. Unless you just want to change it bc it’s torn down already. Buy a honer from the auto parts store and pop it in the drill and go to town on the cylinder. New gaskets, slap it back together with a fresh plug and fire it up! Change the oil as well. i just ordered a complete gasket set for that same bike $38 on amazon. the only thing I would recommend is to change the valve seals since it’s all apart and they come with the gaskets anyway. great pics

@Frank Angerano I got the Head and Cylinder off and the cylinder off. The piston was rusted in place to the cylinder wall. The rings are stuck in also. I guess I can try to hone the cylinder or should I send it to a machine shop? Looks like I might get away with a top end kit and maybe a new sleeve?