Gas tank cap vent

Jay Loeppke jloeppke at
Mon Jul 2 19:51:15 PDT 2007

So  thats the reason I hear a whistle from the cap.    Learn  
something every week about my bike on this blog.
On Jul 2, 2007, at 8:10 PM, Art Lischer wrote:

> Had similar happen in E CO on way to Fandango.  Try fiddling with  
> the vacuum line to the petcock. It might be kinked causing petcock  
> to shut off fuel supply when in "ON" position.
> Also try rearranging the carb bowl vent lines; if the ends of the  
> hoses get in a place where there is air or turbulence it won't  
> allow bowls to vent and slows gas flow.
> Does the cap whistle or whine after sitting a few minutes in the  
> sun?  If so the cap is venting properly.
> HTH,   Art in DM
> Larry Zoia wrote:
>> Gentlemens,
>>   Could someone enlighten me as to a procedure to check whether or  
>> not the gas tank cap vent is patent?
>>    I suspected a venting issue, so of course I shot some
>> WD-40 into the holes and blew them out with compressed air.  When  
>> my problem didn't resolve, I
>> (belatedly) looked in the manual.  It didn't tell me how
>> to check the venting.  It DID tell me not to use compressed air.
>>    During long periods of sustained high speeds (80-90 mph from  
>> Michigan to NJ this weekend) I noticed symptoms of fuel starvation  
>> which were ameliorated
>> somewhat by running with the petcock in the Prime position.
>>    Coming out of a gas stop, the bike, warm, runs great for about  
>> 20 minutes at 85 mph or so, and then the starvation symptoms  
>> begin.  Same thing when I stop to pay a toll with the petcock in  
>> the Prime position.  I tried to look at the glass filter on the  
>> fly to check the amount of gas therein, but that manuever seems to  
>> result in a soft left turn and horns being honked.
>> plan is to check the flow through the inline
>> filter (glass) to make sure the filter isn't the issue, then
>> remove and inspect the petcock for....well, whatever I
>> might find, and then back to square one with the venting.
>>   I do have a recently installed Stage III jet kit, but my
>> mileage has been around 44 mpg for aggressive highway (turnpike)  
>> riding.
>>  I remember hearing what I interpreted as air being sucked through  
>> the cap vent after idling the bike in the
>> garage for a few minutes, and this is what prompted me
>> to blow out the holes.
>>   Thanks in advance for any responses.
>> Larry in Michigan

More information about the GPZList mailing list