The valves get tighter as they wear from slamming into the seats. I would suggest rebuilding top end. New piston, lap valves, shim valves and she will be good to go.
I’m having the same problem right now. Chasing down someone else faults. Bought the dirt bike for $800. Rebuilt the bottom end. Now the compression is hard. But it was like that when I first got it
The valves get tighter as they wear from slamming into the seats. I would suggest rebuilding top end. New piston, lap valves, shim valves and she will be good to go.
I’m having the same problem right now. Chasing down someone else faults. Bought the dirt bike for $800. Rebuilt the bottom end. Now the compression is hard. But it was like that when I first got it