That starts to help us out. Is this a stock or modified cylinder? Is the Keihin carb a PWK or PWM (if you don’t know the difference you can do a quick search as there are some pretty easy visual cues)? Did you buy this kart/motor combination used?
If you wouldn’t mind, snap some pics of various angles of the motor and send them to me at firstname.lastname@example.org. I have a gut feeling and rather than speculating on the forum I’d rather just confirm my theory and go from there.
Back to jetting… My references are probably not going to mean much given a number of differences between my setup and yours; however, at the end of the day your best bet is to learn how to read the spark plug and piston. I highly recommend taking a look at “Firestone Kart Info” and consider purchasing his articles. A few of his articles discuss specifically how to read the spark plug and piston and include some very good photos.