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Discussion Starter #3
If a Suzuki gs 1100 has vacuum carbs but all the vacuum lines are blocked off and the petcock doesn't have the vacuum lines either will the bike still run ? What will lift the carb slides ?
 

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If a Suzuki gs 1100 has vacuum carbs but all the vacuum lines are blocked off and the petcock doesn't have the vacuum lines either will the bike still run ? What will lift the carb slides ?
No and sort of but for different reasons.

vacuum line to the petcock moves the petcocks diaphragm so if not hooked up the bike will run with whatever fuel is in the bowls then it will starve. Without more fuel being supplied it won't run.

Now, will a cv carb allow the bike to run with the vacuum ports blocked? Yes, if it has fuel. How? Well the cab is designed to run at idle so there is enough of an air leak for the bike to run off the idle or slow jet. There is a butterfly valve in each carb body, when it opens the engine revs up, pulls vacuum and the slide lifts, but with the slide not lifting, the butterfly valve would just let more air in, so the bike will appear to rev normally when not under load. It basically acts like a very small conventional carb. However when you put it under load you'll notice there isn't enough power to do work so the bike will be really slow and stall a lot.
 

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Discussion Starter #9
So it will run with just blocking off the 2 float bowl vent / vacuum lines and running the vacuum petcock or is it best to just run a non vacuum petcock. Do those cv carbs need the vacuum petcock ? What is your advice on a project like that ? Keep all the lines or ??
 

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find out how it should have been from the factory and keep it that way until you understand the implications of what you're doing.

i expect you're confusing terms and functions. the vacuum part of the cv carb is under the top cap of the carb, and has no external input. any vent hoses for the carbs need to be open as they are vents. any manifold vacuum ports/lines (which is what this seems to be about) need to go to whatever they are meant to be activating. unless you have removed that part to be activated, in which case it needs to be capped.
 

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OK - the vacuum hose from the fuel tap should go to either the inlet port rubber or the top front of one of the carbs. The float bowl vent tubes are down between the carbs and SHOULD NOT BE BLOCKED OFF. You bike will run like shit if you cap these or join them together or anything else stupid.

If you switch out the fuel tap to a non vacuum type, thats OK but you need to cap the vacuum port as above.
 
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