In need of an answer from someone I just got a 39mm round slide mikuni and put it on wifes 350, but on the throttle cable adjuster on top of the carb has no boot on it and its pretty sloppy at the cap is this a possible air leak or should it be OK?

It needs a rubber cover or it will leak. You can go get some heat shrink that works pretty good

Or use fuel line. It will leak without anything to seal it up. Those rubber boots suck too.

What did you end up doing for this?

well thanxs to all the smarted people than me and a great idea of fuel line it solved my problem. I tried the shrink wrap first but it wouldn't cover the hole going into the cap on the carb, actually I used vacum line it fit over the stem nice and snug and into the cap,solve all those problems and thanxs again guys.
I'am thinking of all of you as I eat this HUGE chimichanga from MR Gs in yuma if you've been to Yuma then you know what I'am talkin about

Another thing you can use is the stretch-it rubber type tape that self bonds/welds to itself.
It's good shite,the proper stuff will will even mend your radiator hoses,which is of course under high heat and pressure.

This ONE time...at beach camp Downunder.....me and Mates leaving the beach after a great weekend's camping,drinking,fishing,drinking,buggying,drinking,surfing,snorkeling,drinking,the heater hose cracked the shits while trying to 4 x 4 up the dunes outa there, and started spewing coolant and steam.Out with the Mend-it tape,worked a treat,and got us home 130kms away.
Now this was ONLY mean't to be a temp fix right? But me and my newly aquired Mate Al Zeimer, totally forgot about it!
6 monyhs later!...when I realised ...I swapped out the hose for a new'n.
Keep some in your man-buggy-bag at all times,has got me home,racing,more than once....would'nt leave home without it.

I used "electrical insulator tape" on my leak-tester and have repaired a clutch cable jacket or two with it, but mainly use it for securing wire-nuts. It's stretchy rubber tape that, when stretched, gets very tacky and sticks to itself. It's in the electrical aisle at the big-box stores. No, not vinyl electrical tape. It's rubber "insulator" tape.