POOGS - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
From the gas tank to the carbs
All fuel system discussion

  • 1 Post By NIBiker
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post #1 of 3 (permalink) Old 03-08-2017, 06:29 PM Thread Starter
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So, on Sunday the phantom out of Gas syndrome struck! I checked that the carb vent pipes were clear and the vent pipe was not pushed too far into the hole in the back of the filter pod (although I did cut it at 45degrees) I also stripped the fuel cap and flushed it out with some solvent spray, the neoprene valve flap looks fine, I also flushed the vent hole in the tank through to the trailing rubber pipe below the engine! Had the bike out tonight ( about 10 mls) and a good hard run, 100 mph in places with no signs of fuel starvation. But one thing I did notice when I got home (no, not the blue flashing lights and sirens! ) Lol! Was that I could hear the tank sucking air, when the tank cap was opened there was a hiss! Is this normal? I can't say I've noticed it on any other of my bikes! Can the neoprene valve be done away with and would this help in letting air into the tank better? Has anyone modded this?
I'll probably leave it at the moment until I get a longer runout to see if there are anymore fuel starvation issues and take it from there!
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post #2 of 3 (permalink) Old 03-08-2017, 08:17 PM
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You should hear a high pitched whistle after filling up with gas on a hot day (i.e., cold gasoline expanding in the hot tank) or after a long hard ride (i.e., air filling the void that the spent gasoline use to occupy). This means that the system is venting properly.

Some on this forum have removed the little neoprene valves and the plastic fuel separator inside the gas cap. This will eliminate POOGS caused by clogs in those valves (which is probably most of the occurrences), but not POOGS caused by blocks in the rest of the line.

I think the weak point of the systems is the 90 degree bend in the plastic fuel separator piece (see below). It is the narrowest point of the whole air line that even a grain of sand could plug.

Chris Glennon - Portland, OR
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post #3 of 3 (permalink) Old 03-09-2017, 03:01 AM Thread Starter
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Thanks for the info, I presume the valve stops fuel leaking if the bike is dropped too!
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