I am running the following with my 76 KZ400, stock engine, electronic ignition from later KZ440, mac slip on muffler, Mikuni VM30s. The 230 mains seems high compared to recommended set ups from Dime City, Sudco, etc. and what others have reported - most in the 190-230 range but they work well for this bike.
Main Jet: #230,
pilot jet: VM22/210 #25,
Throttle valve cutaway (slide): 2.5
jet needle: #6F5 on #4, (STOCK Needle, 1 Clip Richer)
Air Screw: 1.75 turns out
needle jet: #159 P-5, (STOCK)
air jet: BS30/97 2.0, (STOCK)
needle valve set: VM34/39 3.3, (STOCK)
float height: 22-24mm (STOCK)
Hope that helps.
