Question for the Carbmeisters

[thewiz]

I just cleaned and inspected the VM33 Mikuni smooth bore carbs on my 80G. Was kinda' fun cuz nearly every hole was either plugged or had junk in it .... so I pretty well knew it would purring or growling (it has a SuperTrapp too) soon. Put the carbs back on, flipped to prime and almost before I could hit the starter button, gas came pouring out of both vent tubes (not connected to the box) and the airbox itself. Hmmm ...... no way would it start or self correct the flooding.

I then took the tank back off, put it aside and decided to check for spark. Had plenty and it nearly started on three .... put the plug back in and it fired right up. Strong and snarly .... just with the fuel in the bowls but no tank on. Wheww hoooo !!

Hoping that it had self corrected, I hooked the tank back up and it flooded again the same way.

All floats were set to 3/4 inch ... 18-19mm .... by whoever worked on it before me and I didn't mess with 'em. That is very high compared to the stock XS carbs as we all know .... which very well may be meaningless because the style of carb is quite different ..... BUT ....

Could the float level be set up so high that the fuel NEVER shuts off at all before gushing out the vent pipes OR because of an high float level, could the float drop be so long that the needle is getting jammed up and never seating? Needles looked good under magnification but could they still be bad? Does anyone know what the float level and drop spec for this type of carb should be? The PO said it ran awesome with these carbs on ... was due to an ignition problem that I ended up with the bike.

[mro]

Some where on this site you should be able to find all the info on your carbs.
http://www.sudco.com/onlinecat33.html


mro

[thewiz]

Thx, M .... Would that it be so .... I have their catalogue in print but I couldn't find a float spec. Actually even called 'um and found that they were pertty quick to refer me to J&Pcycles.com and I haven't found out much there yet either. Was hoping a member of this forum may know .... can't help but think someone out there has that expericnce ...

[mro]

If your carbs match one of these then (23 mm)
scroll to bottom.
http://www.cyclewareables.com/pages/...kuni_parts.htm


mro
my flat slides are set at 17mm

[TopCatGr58]

Hey Wiz,

I found the info from the Official Mikuni VM carb guide found
HERE , and it states it's .86-.94"/22-24mm for the VM32-33 series!?

The diagrams don't show these necessarily as flat side, but cable controlled slide vs. Vacuum controlled slide!
T.C.

[thewiz]

and so the mystery unravels ....

thx again, MRO & TC ..... looks like the floats were probably set to a flat slide spec, like yours, M, by the last shop that wrenched on it.

These carbs are round slide, cable controlled (push pull). Main jets are set down one size to 127.5 .... every other jet and needle and the throttle valve are just what the Sudco books says it should be for the XS11.

Betcha' when I change that float level down some, it won't drown any more .... I sure hate takin' these carbs off and on so .... guess I'll get some new float needles too.... "an oz. of prevention ......"

Thanks again, MRO and TC for the detective work .... I was pretty much flat out of ideas on where to continue looking for info. These bikes wouldn't be a whole lotta' fun to work on at all if it weren't for guys like you.

Steve

[mro]

Thanks again, MRO and TC for the detective work .... I was pretty much flat out of ideas on where to continue looking for info. These bikes wouldn't be a whole lotta' fun to work on at all if it weren't for guys like you.

Wish mine were as easy to find. I've yet to locate an "exact" match for my flate slides. Several that are close and have used info from here and there to get em going. Posible that who ever had worked on em way back when had access to some after market jets etc...


mro

[thewiz]

Do you know the model number? I have a pretty extensive book with pics and specs/jet sizes/part numbers for most Mik performance carbs but nothing on Keihin. I've also got some pretty good pics .... lemme know .... maybe we can zero in on it ...