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Mikuni smoothbore carbs throttle?

  • Thread starter Thread starter vadimg
  • Start date Start date
V

vadimg

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I have a set of 32mm Mikuni smoothbore VM carbs on my 1980 GS1000G. I've never worked with VM carbs before, so I'm not sure what to expect. My question is this: when I give some throttle, then release, it takes a little while for the revs to come back down. The basic effect of this is that I'm not getting much engine braking on the freeway at all.

In all other respects, the carbs idle great and the bike pulls strong from idle to redline. It doesn't look like anything is sticking, as soon as I release the throttle, the butterfly valves slam closed. Since the slides are directly linked to the throttle valves, they shouldn't be sticking, right? Or is it possbile that the slides are still sticking even though the butterfly valves are closed?

Basically, my question is, is this normal VM behavior or not?
 
If the bike is taking time to come back to idle or lower RPMs it SOUNDS like it might be jetted a bit on the lean side to me...off course, it could be something as simple as youve pinched the throttle cable between the tank and frame too...
 
Are there 2 cables? If not, you need both cables because the second cable pulls the throttle shut. One cable opens the slides, the other closes them. You COULD end up dead with only ONE cable & the throttle hung open! Ray.
 
Having a similar problem with my 700, the throttle releases real slow...cable is not pinched anywhere? its not running yet so poses no danger just cant figure it out.
 
Joe, check your grip on the throttle side. I've seen it cause the problem you are having. Ray.
 
Vad, are those VMs or CV carbs? If they have a butterfly, the slides are NOT connected to the throttle cable. If they ARE CV carbs, they are too LEAN & the throttle is slow in coming down because of that. Also, if they are CVs, there WILL only be ONE throttle cable. You need to start with a CORRECT adjustment of all the mixture screws & then go on to the needles & main jets from there. Ray.
 
vadimg said:
I have a set of 32mm Mikuni smoothbore VM carbs on my 1980 GS1000G. I've never worked with VM carbs before, so I'm not sure what to expect. My question is this: when I give some throttle, then release, it takes a little while for the revs to come back down. The basic effect of this is that I'm not getting much engine braking on the freeway at all.

In all other respects, the carbs idle great and the bike pulls strong from idle to redline. It doesn't look like anything is sticking, as soon as I release the throttle, the butterfly valves slam closed. Since the slides are directly linked to the throttle valves, they shouldn't be sticking, right? Or is it possbile that the slides are still sticking even though the butterfly valves are closed?

Basically, my question is, is this normal VM behavior or not?
Click to expand...
ok it sounds to me like those are CV's because the VM smoothebores don't have butterfly valves
as rapid ray said if there the cv's and i'm fairly sure they are then your too lean and you should follow what rapidray said
alsoVM smoothebores only came in 2 sizes 29MM and 33MM
the 32MM you refer to is a CV carb size
hope this helps you to figure out what carbs you have
post a picture of them if you can then i'm sure that they can be correctly identified and you can go from there
 
jwhelan65 said:
Having a similar problem with my 700, the throttle releases real slow...cable is not pinched anywhere? its not running yet so poses no danger just cant figure it out.
Click to expand...

Even with the new cable I sent your way? :confused:

If so, then I would agree with Ray. Especially if new grips were installed.

Did, you change the grips, or still the old ones?

If you have not done anything to the throttle control yet, it could be crud between the throttle tube and bar as well.




Yep, butterfly valves, usually mean CV carburetors.
 
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