In disassemblying my YS110 I noticed that the wrist pin is a very tight fit in the piston and conrod. Is this normal?

Normally they are not that tight. Why did you take it apart?

Hi Dave,
Thanks for your fast response! I took the engine apart because after a recent flight, I found that the engine felt rough, felt like metal grinding, when I hand turn the prop. so I wanted to check what the cause was. I suspect it may be the bearing, but I only had no more than 20 flights and it has been running rich during this whole period and it had been running beautifully. I also gathered from the Ys spare parts list that the cylinder head and liner comes together as one part. Is that correct? Thanks again for your advice.
mck

The cylinder and liner are 1 piece, unlike the 2 piece version of the early 91.

Hi Dave,
Thank you for help, very much appreciated!

Good flying!