What’s up with these small ports on 61x cylinder?

[jeepcreepcj]

I suspect this new to me cylinder was re sleeved at some point, and would like to hear others opinion about it. The intake ports are very small compared to a cylinder that I believe to be the original unported sleeve. Most of the difference is the height, they all start at a similar depth in the cylinder but are shorter than stock ports. Also the stock transfer ports stop at the same height across the bore where these are staggered at two heights. Anyone see this before and know what brand sleeve this might be?

I expect this will be a significant decrease in performance over stock. I am considering enlarging the ports to match the stock sizes, any reason not to do so?

Pics are of the used stock cylinder and one I am questioning. You can see in the pictures that the ports are visibly shorter. I would guess they are 2/3 the height of the stock ones, but haven’t measured them yet.

 

[jeepcreepcj]

Here is two intake ports on either cyl height measures approx 9.38 Vs 12.35

 

[jeepcreepcj]

And the other pairs the sleeve port height is approx 10mm vs 14mm

 

[Jr.]

Looks like a SBT cyl resleeve w/ WSM sleeves! If you intend to run it in a performance application?
You should probably get a better cyl with oem sleeves!

 

[jeepcreepcj]

Yes looking for best performance on a freestyle rn Superjet. Had a ported 61x cyl on it’s last 84mm bore with Wiseco Pistons and seized it up on breakin. So not looking to downgrade this much, at least for long term.

Might try and match the ports to the stock one so I can get it back on the water for now while I have my spare stock one bored and ported.

Thanks for the info