1980 GS 550 L Carbs, BS or VM?

[dfinnegan71]

As stated above, I'm not sure how to tell which ones I have. This bike definetly has Mikuni's on it. I need to order the o-ring set from cycleorings and I don't know what these carbs are called. BS or VM? What does these letters even stand for? Big Spender, Vacant Motel?

[tkent02]

As stated above, I'm not sure how to tell which ones I have. This bike definetly has Mikuni's on it. I need to order the o-ring set from cycleorings and I don't know what these carbs are called. BS or VM? What does these letters even stand for? Big Spender, Vacant Motel?

Depending on which part of the world you are in, it probably came with BS carbs.

[dfinnegan71]

Northeast USA. Probably BS carbs, sounds right.

[cowboyup3371]

The 1980 550s came with BS carbs based on the parts fiche

[7981GS]

Square tops like these on the left, they are the BS (CV) carbs...



Edit: Better examples.

BS carbs...



VM (slide) carbs...




Eric

[Steve]

You will hear your carbs described as both BS and CV carbs.

BS is part of the model name (BS32SS). CV is the type of carb. CV stands for Constant Velocity, which refers to the velocity of the air through the variable-venturi area that is controlled by the slide.

The older carbs are VM, because that is part of their model name, VM22SS.

Even though the carb tops that 7981GS showed appear to be round, he was referring to the four retainer bolts that are arranged in a square.
The VM carbs have lids that are more rectangular and only have three bolts on them.

EDIT: Eric, nice addition of the comparison photos.

.

[dfinnegan71]

Thanks guys! I do indeed have BS carbs. My Kawi has the VM type show in the pic's. Thanks for droppin some knowledge on me!

[BassCliff]

Hi,

Feel free to visit my little website. It has lots of "how to" guides with lots of pictures. You might pick up a few pointers to help you maintain your bike.

Thank you for your indulgence,

BassCliff

[dfinnegan71]

Thanks Basscliff, cliff burton fan?

[BassCliff]

Hi,

Thanks Basscliff, cliff burton fan?

I was not a big Metallica fan, but I do play bass. I started playing in little rock bands in the late 60's and then moved on to big band jazz in high school and college. My idols during my formative years varied from Pete Cetera (Chicago), Stanley Clarke (Return To Forever with Chick Corea), Jaco Pastorius (Weather Report), Ron Carter, and later to Victor Wooten, John Patitucci, Tal Wilkenfeld.

I don't play a lot of jazz these days. I sort of gave up music and joined a country band. It's good if you can make some money when you play.

Back to the subject, here's a rack of VM carbs:



And here's a rack of BS32SS carbs (also called CV carbs):





As has been stated, in most of the world the '79 models used VM carbs and were changed to the BS series in 1980.

Thank you for your indulgence,

BassCliff

[dfinnegan71]

Thx for the diagram's Basscliff. I notice the the hose on vaccumm port #2 pushed air out than sucks it back in while I'm crankin it over. Should I have the tank on and this vaccum line hooked up? I'v been gravity feeding it gas with a water bottle and fuel line attached to the carb.
Victor Wooten is a MONSTER!!

[thewiz]

Plug it with a proper sized rubber cap if you are using an auxilliary fuel tank. Then hook it up to the petcock when you put the tank back on.