VM33 smoothbore quandry

[Guest]

OK, scored a very nice set of Mikuni VM33 smoothbores for my GS1100. Already jetted for a stock bore 1100EZ engine @ sea level with a V&H 4-1 street megaphone. These are different from the Keihin smoothbores I have seen;

There are large vent "ports" or nipples on the right side of #1 & #3 carb bodies, and smaller ports on the left side of #2 & #4 carbs. There is no central fuel intake point on the fuel rail that links the carbs, as the Keihins or stock CVs have. I would imagine one of those ports is for fuel, and the other 3 are float vents?

Which is for the fuel and which are the float vents??

[Guest]

IIRC There are 2 vent hoses, one fuel port, one capped (secondary fuel) and one vacuum port. I am pulling the tank tomorrow and give you an exact breakdown by carb.

[Guest]

That set up makes sense to me...I was thinking/hoping the bigger ports were the float vents, and the smaller ports were the vacuum and fuel...but all other smoothbores I have seen require the petcock to run on prime. hopefully I'm wrong!

I greatly appreciate the help!

[Guest]

Got John's diagram this evening...there is in fact a very hard to see vac port on the left side of #3 carb, toward the front of the carb body. Cap was almost impossible to see with the carbs mounted on the bike, even with a flashlight. I even checked the Mikuni diagrams on Sudco.com, and they indicate it is a vac port. So I'll run a line to this vac port to the vac fitting on the petcock.

SO, from left to right the order is: Fuel, carb vent, vacuum, capped fuel, carb vent.


Thanks a TON, John!!