Piston won’t go up and down. Help!


New Member
Local time
3:17 AM
Oct 11, 2022
I just put my bike back together and upon taking it out for a spin, when I released the clutch it seemed like the whole thing seized up and the back wheel wouldn’t move. It took a lot of force to just get it to turn over even once. What I noticed is that when I take the head off, or take the spark plug out, it cycles up and down just fine! The second I tighten the head bolts and create a seal, it acts like it’s seized up. Is this a compression issue?

what’s going on here?
These engines take some leg power to start. If you just take spark plug out, can you roll the bike around & hear the piston moving.
Update: seems the engine has exploded. :)


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Update: seems the engine has exploded. :)
You got to disassemble that for us all & show us pics of the carnage. Sorry to hear you lost a engine. It happens! I had a engine I didnt even make it thru break-in period & the crankshaft broke.
Yeah it could of lost a piston pin clip & the piston pin worked out of the piston & jammed into a transfer port. Resulting in a locked up engine & broken parts.