My ys 110 engine has been causing problems the last few weeks, it dies /cut off when I open throttle after being in idle speed for more then 20 seconds.
Today I noticed there is hardly any pressure when turning the prop either when engine warm or cold. The prop swings almost freely with a little counter pressure.
Assuming valve clearance is correct Seems I need to change a piston ring again. Can a ring be changed without changing the piston sleeve which in this case is a full engine head?
This engine has been serviced 10 months ago and engine head +piston were changed. Since then was used for 70 hours.
why does presure loss happens after 70 hours ?
I try to prevent the engine from getting too hot, using cool power 20/20 and lately 30% Heli fuel. (air tempreture july august is 84-90f)

help needed....
[&o]