Last year I was riding my motorcycle, and the motor turned off while driving. It was a harsh stop, it didn't die slowly like when there is no fuel left. After checking the compression (which didn't exist) and taking apart the motor, I found the issue which was a slight piston jamming.
I purchased a new cylinder kit (with piston and all gaskets) and installed it according to a well documented guide.
Now I have compression, but it is very low. 4 to 5 bar max. I read online that this motor should have around 10 bar.
Nevertheless I installed the motor to my bike. It starts successfully but dies off when opening the throttle. The motor only starts revving when the throttle is opened very gently (like 5%)
I already tried another cylinder head (which also was from a motor that got a piston seizure) but the results were the same with 4-5 bar.
Maybe someone has an idea what i could try next, before i get ripped off by my Yamaha service center.
The bike is a Yamaha WR125R 2013 Model (4 stroke, 1 cylinder)