Google "Honda vt500 single carb" there's a pretty slick conversion a guy did on a Shadow 500, It's on the hondashadow.net forum, he uses a single 36mm Mikuni carb.
For good power output need for every 100 cc 6.5 c2 of cross section of carb.
6.5 x 5 = 32.5 it is square of diff of carb in cm. for 500 cc motor.
Diam of card = 64.34 mm it is good carb for 500 cc for get full power.
36 mm it is for about 175 - 200 cc motor.
36 mm don't give full power with 500 cc motor. With 36 mm carb You will not use 300 cc of yours motor it mean You will get only ~ 1/2 of available power of 500 cc motor.
For VT500 each cil 250 cc need minimum 45 mm carb for good power output, 36 mm insufficiently for 250 cc each cil.
