I have not taken the DS motor apart yet and was wondering what is the Notch for at the lower part of the cylinder/skirt?

 

Did you buy a scrap cylinder for you AL conversion then?

Or will you just send in yours when you disassemble it and paid a core charge?

 

I bought a used parted out 650 cylinder in great shape. I like having a backup stocker

 

when you insert the piston into the cylinder and get the oil rings just beyond the bevel on the bottom of the cylinder, this rounded notch allows insertion of wrist pin. the stocker has a rounded notch the radius of the pin, I see in your pics that millinium tech has given your new cylinder a much larger window. the cylinder squirt only needs to be full length on the two sides that the piston has squirt