Yanmar 2tr20a cylinder help

[bridgeport13b]

Hi I have a ym2000 that needs engine bearings, anyways cylinder bores are very clean looking but I have a ridge at top of cylinder liner that looks more like a taper. Basically the carbon ring at top seems to be undercut compared the the surface the rings ride on. So I知 not sure if the taper is factory or if someone took a ridge reamer to it.

 

[bridgeport13b]

Here are the pictures Imgur: The magic of the Internet

 

[HoyeTractor]

That is the way those are made. I'm not sure what the purpose is but they are all that way.

 

[bridgeport13b]

Hi Aaron appreciate it

 

[careyo63]

Heard that!!! If or when I have to get into mind I would have thought the same.