The mainfold stub-out and the Mikuni intake should not touch each other or 'icing' can happen.
Most Mikuni kits come with a cheap radiator hose to join the two, and last's about one year if lucky.
Took a while to get this right on my bike- used 1-3/4" long rubber hose for automotive gas-tank filler, had to buy 4 feet but also had to buy an 18$ tool to cut it off flush.
Different kits came with different manifold stubs.
Just some thoughts- agree with Mr Pete as to "it should run as sweetly as any single-carb engine."
Stalls without throttle assistance.
You should not be using throttle with enrichners on- see the Mikuni manual!
Have some rubber left- send me the lenght you need and will cut to suit- only need postage $ and good to go!