Engine won't turn
 

450 foreman won't turn over. Thought originally it had siezed up. It will turn fine without the spark plug. So i took a look at the valves. No damage there. After adjusting the valves it started to turn. Turned over but wouldn't run without the choke pulled fully. Smoked like crazy. After about a minute of trying to start it siezed back up. Is the timing chain stretched?

Engine won't turn
 

if its been sitting you may have no lubrication, and if you have to use full choke its likely the carb needs cleaned

Engine won't turn
 

Could the cylinder be full of water, or say gas from an overflowing carb?

Liquid won't compress, so if there is some in the cylinder, that would cause the motor to lock, but turn freely if the spark plug was removed...

Engine won't turn
 

I messed with the valves some more and got it running. Smokes really bad and sprays oil out the exhaust. I guess those valves weren't ok after all. I'm gonna rebuild the top end

Engine won't turn
 

O boy. . . Sounds like sombody cranked the valves down to try for a better seal. . . rebuilding the head won't do you much good if shes throwing oil out the exhaust. . .

Time for a Jug n Piston assembly. . .

1. Piston.
2. Rings.
3. cylinder.
4. Feul Filter.
5.Carb kit.
6. Spark plug.

replace these i bet it run perfectly. . .

Mikey !

Engine won't turn
 

There's discoloration up the exhaust valve. Is it possible the oil out of the exhaust is getting in past the stem seal. There's still good compression and no marks on the cylinder wall

Engine won't turn
 

Stem seals can leak oil.