I'm not an expert, but I have the 88+ small reed cylinder and purchased a new modified carb from Jerry Hall. The carb is a TM38-85 that has been bored to 41mm and the air correction jet removed.
Here is Hall's recommendations for carb setup I have saved:
"ONLY USE GENUINE MIKUNI JETS!!!!!!!!!!!!!!!!!!!!!!!!
Lid on the air box, foam filter 350 to 390 main jet
Lid off of the air box foam filter 380 to 470
Pilot jet 22.5 to 25
Needle 6DK3 2nd or 3rd clip position from top
Needle Jet R-0 to R-6 389 series
Air screw 1 1/2 turns out from the seated position Plus or minus 1/4 turn
No air correction jet
4.0 slide
3.5 needle seat
float arm parallel with the gasket surface (without the floats touching the float arm)
If your bike does not run good and reliable with the above jetting range YOU HAVE OTHER PROBLEMS WITH YOUR ENGINE OR ELECTRICAL"