Vented fuel tank query.

[Adie Porter]

Hi Guys, im swapping out the carbs and airbox for a top tank and flatslides.
Fuel cap in the fake airbox cover.
What im interested in finding out is, do i need to vent the tank or just use a vented cap?
I am looking for the flush harley style push in to pop up filler cap. How much venting is needed if the carbs are sucking the fuel down, also im in a hot climate and the fuel can expand.

 

[MaxMidnight]

As long as the air pressure in the tank is the same as ambient I don't think it matters how you achieve this.

 

[Adie Porter]

I dont have to calculate what fuel is being sucked out and compensate with a particular dia of hole for air flow in? Am i looking too deeply into thia?

 

[MaxMidnight]

Am i looking too deeply into thia?

Possibly.

I doubt (but am happy to be proven wrong) that as long as the vent hole is (say) 1 - 2 mm that would be sufficient.
I doubt that the volume of fuel drawn even at full throttle is so big that a small hole will allow the ambient pressure to be maintained.

 

[Adie Porter]

Thanks for that MM.

 

[Fire-medic]

I used a small drill bit and got a rough measurement of the OEM gas tank vent dia. which is 0.8mm or 1/32".

 

[wayne billings]

Goood morning- What does one do about repairing or replacing the fuel cap rubber . thanks wayne b

 

[Fire-medic]

Goood morning- What does one do about repairing or replacing the fuel cap rubber . thanks wayne b

Gas Cap Manual / Tutorial for Dry Rotted or Cracked Gas Cap Seals

Want to replace your gas cap seal and not loose having one key for all locks? Well, now you can with this tutorial. My gas caps seal was cracked, so I originally started to see if I can just replace the gas cap seal, one thing led to another.... I figured out how to replace every piece down...

www.vmaxforum.net

 

[wayne billings]

Fire-medic hello again . the gas cap on my '86 needs a rubber seal. I serviced the cap and is working well. I cannot locate a seal. thanks again and I hope you are doing well. wayne b. [email protected]