It is sometimes hard to know what a carburetor is really capable of, unless you know the "Sweep area" or what you may call the "true Throat size". I have done some measurements at work and some math and came up with some comparative #s. In the old days it was simple. you had a round hole and you would figure out the area at the most constricted part of the venturi. This was virtually always the size at which the carbs were listed, IE 26s had a 26mm hole and in turn had an area of 531 MM/sq. When BS carbs came out, the hole became oval and the listed size became only the opening size where the carb met the boot. The actual throat was something completely different. When you see these #s you may change your mind about the choice of your carbs. Here are the #s. I placed these on the list in order of actual ascending size of venturi. Not listed size.
VM24 (KZ650) 452.4 mm/sq
VM26 (KZ900/1000) 531.0 mm/sq
VM28 (Z-1/Z1R) 616.0 mm/sq
VM29SB (aftermarket) 660.5 mm/sq
BS34(CV)(1981+ KZ750/1000/1100) 735.0 mm/sq
BS36(CV)(GS1150) 806.0 mm/sq
VM33SB (aftermarket) 855.0 mm/sq
TM34SB (flat slide) 908.0 mm/sq
this might help some of you to chose the right carb for your bike.
Otto
74 Z1-A stock
76 KZ-900 Totaly stock vice MAC pipe
77 KZ-1000A stock
78 Z1-R 100%MINT 500 original Mi.
78 Z1-R Yoshi 1103 kit stage 1 cams Yoshi pipe. Etc
79 KZ-1300 (1400)
80 KZ-1300
81 Scratch built GPz1150R
82 KZ1000
