I was not aware that Mikuni ever made a 39mm TMS, maybe someone bored this one. The TMS series was discontinued many years ago, so I do not know if new slides, needles and float tower assemblies are still available.
I did not invest in all of the TMS & TMX needles, pilots and slides so that I could try to tune these carburetors. These carburetors did not have an adjustable air correction or adjustable needle jets. Not having the ability to change the air correction or needle jet limits how well a carburetor can be tailored to an engines specific needs and to the usable life span of the carburetor. The Keihin PJ, PWK, PWM and Air Striker also lack these two adjustable circuits.