64 miles completed and all seems well. Its had every chance to break down and it didn't.New leads, ignition coil and the petrol cap has a hole top and bottom. Only issue is I brimmed the tank and I can smell petrol now. Guess I will have to come up with a solution. Im thinking I need to build a vented cap, a bit like my CB1100R has. Maybe a bleed nipple and a long hose dropped down by the front beam will do the trick. Dare I ask what everyone else has done ?

Thanks again ,

Regards

Nat.

Hi Nat,

Model car fuel non return valve available on the bay of E

Cheers H

Hi Hunter...................thanks. Am aware of non return valves. Id just be interested to see how people have fitted them to their petrol cap.

Thanks,

Regards.

Nat.

Or just don't overfill the tank...simples...

I have use the original small tube that pokes out of the tank at the top rear corner...

I ran a long fuel hose from there and looped it few times up in the top corner of the
bonnet section.

I have fitted a windscreen washer jet there and it serves as my 'vent'.

Did the same to Sally's....

Thats nice and clever. My tank has everything sealed up and the filler neck takes a VW screw cap. I dont really want to dismantle the front end , take tank out and fanny about at the moment, so looking to do something with the cap. Was thinking along the lines of a bleed nipple with a hose and a one way valve on the end . Interestingly ( or not as the case may be )I bought a locking petrol cap and it doesn't fit becaise I dont have the clearance between the top of the cap and the bonnet cap. Thus this will limit any cap modifications. I may have to just leave it as it is ( and not over fill the tank )or buy another cap and just drill a hole in the bottom of the cap and hope that where the body of the cap meets the cap top there is  enough of a gap for it to vent.
I have dismantled a cap and there is the mechanism inside that acts like a ratchet to prevent the cap being over tightened. The neatest solution would be to take a cap apart , remove the mechanism and the cavity left would allow room for a 1 way valve to fit inside. I would then need someone to weld it together for me and neaten it all up as taking the cap apart is not easy and does mangle the top part a bit. Obv would need minimal welding as you dont want to melt the insides of the cap ( rubber hose ). Thats a project for another day but would be really neat.
Anyway, I now know what I need to do.

Regards,

Nat.

Just a word of caution, as I`m hearing the terms "one way valve"

You need a valve to allow air into the tank for when the fuel is used up, as vaccuums can cause a problem, as we all know. However, if you only have a one way valve, it can allow pressure to build up inside the tank, and in my own case, its what killed my Buggy last year. I had a two way breather valve that failed on me, and in doing so pressurised the fuel lines during hot sunny weather. The end result was that the resultant pressure was enough to force the float chamber valve to open and to flood the cabs to such an extent that the fuel ran down the insides of the carb, filled the barrels and my engine oil is now 98 RON as a result.

There are a few different solutions out there, but you need a breather valve, not a one way valve   

Quote from: Dave DND on April 15, 2013, 12:48:12 PM
Just a word of caution, as I`m hearing the terms "one way valve"

You need a valve to allow air into the tank for when the fuel is used up, as vaccuums can cause a problem, as we all know. However, if you only have a one way valve, it can allow pressure to build up inside the tank, and in my own case, its what killed my Buggy last year. I had a two way breather valve that failed on me, and in doing so pressurised the fuel lines during hot sunny weather. The end result was that the resultant pressure was enough to force the float chamber valve to open and to flood the cabs to such an extent that the fuel ran down the insides of the carb, filled the barrels and my engine oil is now 98 RON as a result.

There are a few different solutions out there, but you need a breather valve, not a one way valve   

Good point 

A fair point, very well made. I have ordered a new cap and will try it wil just 1 hole in the bottom..............

See how that works.

I guess at some point I will have to remove the bonnet and do a proper job.

Thanks,

Regards,

Nat.

Hi Nat,
2 holes will leak, mine has been done for a while with no problems but brimmed it friday parked across a slope saturday with the filler down and it seeped out and made a bit of a mess.
now looking into a 2 way valve assy to go inside attached to the bottom of the cap.