Seized MS290?

[kyle23]

Good morning, I have a MS290 that recently seized up. Went to pull the starter rope and it pulled a few times then locked up. I pulled the recoil assembly off and it pulls freely, pulled the flywheel to see if there were any obstructions behind it and nothing. Pulled the exhaust and this is what my piston looks like. I did recently install a new 390 piston and ran a few tanks of fuel through it. Any insight on where to go next? Any help is appreciated thank you.

 

[coffeebrk]

Did you do pressure and vac test?

 

[pioneerguy600]

Is it locked up solid, did you try turning the flywheel by hand? If it is solid locked could be a circlip has come loose, very probable if the new piston and cylinder were AM and even OEM ones can come out if not properly orientated when installed. If a clip gets thrown out the piston pin can walk out and get stuck in a transfer port.