Check out this link: http://www.vintagesleds.com/library/manuals/misc/vmmanual.pdf
It's an old tuning manual for Mikuni's. In it there's an exploded view and it shows the "air jet". I think everybody who takes care of their own sleds and plays with carbs, should read this manual - just my two cents.
A forum community dedicated to snowmobile owners and enthusiasts. Come join the discussion about performance, racing, troubleshooting, trails, maintenance, riding tips, modifications, classifieds, gear, and more!