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gas whistle

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946 views 5 replies 4 participants last post by  dragknee  
#1 ·
if I get the bike out in the sun, to work on it or wash it or something, the gas tank will start to whistle. I know it's the gas tank because it stops when I pop the cap (along with the sound unpressurization) Is that normal or should the pressure be venting on it's own? It's always done this and it's not a big deal, because it doesn't effect mechanics. The noise is just kind of annoying.
 
#2 ·
Yep, The venting is normal, or the tank would bend and the petcock be damaged by the pressure. Be thankfull for the wistle as it is a notice to you that your vent is working. It may even work to keep it clear.

This post brings a thought to me. The high incedence of petcock failures could be related to the tank vent. Or as above if the vent is stopped up a fairly large amount of pressure could be built up in the tank as the air expands with the heat. the spring in the petcock is supposed to hold against this pressure. it;s possable that this could push a marginal petcock seal to leak thus putting thr carb float needles under fuel pressure as well.

Just a thought.

FOG
 
#5 ·
good call about the fuel pressure in the tank causing carb flooding, i'll be that's completely feasible.

more fuel in the bowls would cause the floats to exert more pressure on the needle though, to a point.  depending on how much air there is in the tank, there could be a relative 'lot' of pressure, causing lots and lots of flooding, regardless of float height.

pressure AND gravity vs. two little seals, a small spring, and a light buoyant force... it's no wonder that there are troubles with fuel flooding the crankcase...

ok, everyone clean out your fuel cap vent now.