There is a piece of metal stuck in the piston. Looks like something came apart.

 

Ugh. I wonder if something from the crank came off. Any idea what would be causing the stalling/hard cranking?

 

Well something beat the bajeezus out of the piston. I'd take it apart and cheack things out. I'm guessing that you will feel something binding when you rotate the crankshaft by hand.

 

I actually did that before putting it back together. Nothing binding. Piston goes smoothly up and down. I'll do another little video for you when I can get some generic relay wired in.

 

Did u flush the bottom end out before putting top end on. Looks like u chewed something up,piston ring, skirt or something. Did the crank seem to move smoothly while apart. Might check and verify that the oil pump is pumping it uses a plastic gear that can strip or block it off and premix your gas.

 

Previous post wrote after seeing pic of piston Didnt realize there was a page two. Sorry for the repeat suggestions. U did install the piston with arrow toward exhaust

 

I did. I noticed some carbon build up in bottom of header, bit I was able to blow through it without issue. Everything else though, almost pointing to clogged exhaust... Any ideas?

 

I started it today, fired right up. Ran for about a half minute, started putting out. Pulled exhaust off, and the compression still is too much for the starter to turn the motor over. I pulled the spark plug, and ran the starter for a little while, and drained the fuel bowl. Put it back on, tried to start it, would go about 5 cranks before it went so slow I was concerned about the starter health. I looked inside the head with the spark plug out, and I can see a small ring in the piston, kind of like a mark from where the spark plug is firing. However, there is no mark on the spark plug itself, so I wouldn't appear to be hitting that. In any event, I guess the bottom line here is that once the engine warms up, the compression is so great it won't stay running. I really don't know what else to do with this. I made a huge freaking mistake buying this, and now I don't have the money to just junk the POS and go buy a different one. Definitely going down in history as one of my best eff ups.

 

So is the exhaust plugged?

"the compression still is too much for the starter to turn the motor over"
A LT80 starter is prolly the strongest of any. I've had them spin a motor with over 200 lbs comp with no problems. I think the starter may be bad.

"the compression is so great it won't stay running"
That just don't make sence. Surely not the case unless you mean the pipe plugged.

As I see it, something came apart (according to the pic). You didn't find out what came apart. Either you missed it or you haven't found it yet.
Was both cir clips there? did a ring break?
Where are you located?

 

Nope, it's definitely the case.

Basically, a couple days ago I disconnected the exhaust. I ran the quad until it stalled, just at idle, no more than a quarter throttle on the stand. Once it gets to a certain temperature, after maybe three minutes from being completely cooled, the engine dies out. The starter can't turn the motor over at this point. (Exhaust is disconnected still) If it starts, it dies out immediately, or within a second or two. This time, I take the carburetor off to check the reed valve, which looks fine. I take the spark plug out, and the starter spins the motor fine. No noise, no nothing. I put the spark plug in, and the motor can't be spun over smoothly. I have a car battery, I hook it up, same issue, starter can't turn motor over. Pull spark plug, spins freely.

Literally acts like when the engine is warm, it has too much compression to stay running.

The old piston is complete. A friend suggested that maybe a spark plug came apart at some point before I bought it. The old piston/jug has nothing missing. Not even cracked. Just worn out. I'm in tampa, FL.