Want to Remove Vacuum to Petcock - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 2 (permalink) Old 10-07-2010, 10:16 PM Thread Starter
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Want to Remove Vacuum to Petcock

I noticed that my petcock is rusted shut. It will need to be rebuilt or replaced I'm sure. After doing some searching on here about how to go about doing that, I discovered that our petcocks are vacuum operated. This is the first time I've even heard of such a thing, and it sounds needlessly complicated to me. I'm 99% sure there is no such device on the petcock of my ATV, just a single fuel line to the carb. Why is a vacuum operated petcock needed?

Since I'm going to have to replace/rebuild the petcock anyway, could I just replace the petcock with a "normal" one, i.e. one that isn't vacuum operated? I'm in the process of doing the ear shave and coaster kits, and I'm trying to eliminate as many vent lines/vacuum lines as possible.
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post #2 of 2 (permalink) Old 10-07-2010, 10:52 PM
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The vacuum petcock is a safety feature. If the engine is not running, fuel cannot run into the carb bowls and spill if the float valves leak.

It is really not complicated. Just a single short vacuum hose from the engine to the middle nipple on the petcock which operates a diaphram to open the valve.

You can leave the petcock in the RUN position when parking the bike. It only needs to be turned OFF if you want to empty the carb bowls for service or storage.

I would not change out the vacuum operated petcock out for a non vacuum operated one for the reasons outlined above. JMHO


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