Everything was fine. Piston was in like new condition. The bore has a large ring of rust in it. I will need a new piston since the only way to fix this is to bore it but the stock one looks like it just came out of the box once I cleaned the rust off of it

 

You might want to compare the price of boring against a new jug.
Mike

 

I would consider doing that if I could find a new jug. The best I could find is a company that you mail your jug to and they machine it and send you back a piston and top end kit. They're price is $169 plus shipping

 

Ok, so I just got home from work and I used the bead blaster on the jug to get the gasket off the bottom of it. I figured why not blast the combustion chamber too since the valves were all rusted up. After blasting, the valves looked like brand new but there is some rust trapped behind the exhaust valve. Guess I might still be looking at a valve job after all.

 

And now my theory of what happened: there is no rust up wind of the cylinder meaning the water didn't get in the intake side. I believe the rusted out baffle combined with the goofy looking muffler tip cupped water into the muffler when it rained and the engine was sitting with the exhaust valve partially open. The muffler is higher up than the motor so the cylinder just filled up with water. At least my rings were good enough that none of the water ended up in the crankcase. I should be looking at about $300 to fix my $275 4 wheeler. I'm not heart broken

 

So I got all the parts to rebuild the top end, had the carb rebuilt, out it all together in a couple of hours and she puts like a kitten. It needed a pilot jet and I ended up using a bigger one (42) and it runs perfect. I put some seafoam in the gas and the crankcase then changed the oil the next day. I drove it around for about an hour to get the seafoam circulating. It seems to have some junk in the fuel that broke loose and made it run a little crappy but it runs good for the most part.

Strange thing is that it sometimes seems to have an extremely low rev limiter like some quads have when you put them in reverse. Whenever it seems to do this, turning the headlights on seems to remedy the problem. I find this extremely strange and think I'm gonna be tracing wires and replacing ignition components in the near future,

 

Check what voltage is going to the battery with the engine running, check at various engine speeds, if it goes much over 15 volts, the regulator will be slow cooking the CDI.

 

Your regulator is bad. My quadrunner did the same thing. New voltage regulator fixed it right up. It will get worse with the rev limiter until you replace it. You can unplug the regulator and ride it, but it won't charge the battery.

 

Sounds like the front plastic is coming back off. I have tried to remove that thing before to replace the choke cable but it would not come off. I ended up dropping the gas tank to replace the cable. Nice to know that it's that and not the CDI. Those things are a pretty penny. BTW, I just bought a nice high dollar ATV battery for it the other day and it had a cheapy lawn mower battery before so nothing surprises me.

 

Some voltage regulators are more expensive than the CDI. I repeat, check what voltage is going to the battery with the engine running, check at various engine speeds, if it goes much over 15 volts, the regulator will be faulty. Regulators are usually near a back wheel on a quad.