Fuel Cap Venting Question

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HotFoot
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Fuel Cap Venting Question

#1

Post by HotFoot »

GL1100 if it matters....

Is the OEM cap designed for one way venting? ..... air is only allowed to be sucked in as fuel is used and a vacuum created?

Are there any internal rubber seals?

Hoppy
'81 Honda GL1100 Std
'80 Honda CX500D
'79 CX500C (Stagnant Project)
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robin1731
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Re: Fuel Cap Venting Question

#2

Post by robin1731 »

HotFoot wrote:GL1100 if it matters....

Is the OEM cap designed for one way venting? ..... air is only allowed to be sucked in as fuel is used and a vacuum created? Yes, that is correct.

Are there any internal rubber seals? Internal no, just the seal to seat the cap.

Hoppy
1976 Goldwing Super Sport
1985 Honda Elite
1976 KZ900 Dragbike
1992 ZX7 Dragbike (KZ900 style motor w/NOS)
and a rotation of various purchases
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HotFoot
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Re: Fuel Cap Venting Question

#3

Post by HotFoot »

Thank you! Cap is going to get boiled/ultra sonic cleaning to drive any possible evil spirits out,..... didn't want to bugger anything internal.

Hoppy
'81 Honda GL1100 Std
'80 Honda CX500D
'79 CX500C (Stagnant Project)
Ever Growing SHOP (Shameful Hoard Of Parts)
The Past: Triumph, Norton, BSA, Honda, HD, Kawasaki
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Re: Fuel Cap Venting Question

#4

Post by rcmatt007 »

this is actually why often your hear a whoosh when you open the tank. Engine heat transferred to the tank (as well as outside ambient pressure) may create a little pressure in the tank. Likewise, there may be just a little vacuum that is not enough to overcome the one way valve
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HotFoot
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Re: Fuel Cap Venting Question

#5

Post by HotFoot »

I often hear a muffled little "phhitt" when turning the fuel valve to open, especially after the bike has sat a while. Apparently pressure being released into the fuel line/filter/pump. It's the little "Fuel Elf" in there waking up (passing gas).

Cap has been boiled in water/Pine Sol. Soaked in CLR for a few minutes, flushed with water, Dipped in alcohol to get all the water out. Now on to the fuel filter. A Randakk unit installed about 2500 miles ago. I don't expect to find much as I had thoroughly cleaned the inside of the tank.

This has all come about due to being out last Sunday when about 60 miles into a pleasant ride I did not get good throttle response chugging up a mile long hill. Was in 5th gear, downshifted to 4th (55 mph). A slight coughing so I switched to reserve even though I had well over half a tank. Cough went away but I was a bit anxious for the 25 miles left to get home. I get paranoid about this sort of thing.

Actually reminded me of carb ice indications, (going back 30+ years and a Continental A-65). It was a perfect day for it. 85F and humid. The A-65's underslung Stomberg carb would ice up in a heart beat when power was pulled. I've seen frost externally on the carb body while on the ground. Can't really imagine a Goldwing getting carb ice but I suppose it is possible. I had been going downhill (throttle back) for a minute or so before I cranked on the throttle to chug up out of the valley. Anyone ever think they may have experienced GW carb ice?

Hoppy
'81 Honda GL1100 Std
'80 Honda CX500D
'79 CX500C (Stagnant Project)
Ever Growing SHOP (Shameful Hoard Of Parts)
The Past: Triumph, Norton, BSA, Honda, HD, Kawasaki
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robbie202
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Re: Fuel Cap Venting Question

#6

Post by robbie202 »

i was wondering how to clean the cap. refurbished fuel tank should be here some time next week.
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mrtwowheel
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Re: Fuel Cap Venting Question

#7

Post by mrtwowheel »

The culprit is the same yellow fuel gum that gums up carbs. Any solvent that dissolves gum and is still kind to rubber should work. I've used Walmart Tech Lube, generic WD40, but I've seen this solvent swell rubber before, it worked. Brake cleaner should work, some use Seafoam. Alcohol and carb cleaner are not kind to paint and some rubbers. I think the Honda civic cap is the one that is a good fit for some GLs.

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