Hello

I have a ys120FZ engine that ran perfectly on my G-trick
2 weeks ago I replaced the prop with a new one but so how I installed a wrong prop. Flew the plane for 3 rounds before the connecting rod broke and damaged the piston,valves.
Lucky or unlucky ,a friend of mine crashed his airplane a few weeks ago and damaged his ys 120. Some parts were saved.
He gave me the parts and I replace the broken one on mine.

The replacement piston came with 4 pin hole size on top , my broken one did not have this.
Anyway I assembled the engine but some how there is no compression in the engine. Except for the pin hole checked every thing worked fine.
Started the engine no problem ( just no compression )
Quest? Are the ys120 piston different on other models or are they interchangeable
Or do I have to get a piston without the pin holes?

I might send it to the YS for service.

Thanks

C LIm