Petrol tap and ethanol

[Knowledge]

We have all fitted Viton seals to our engine in order to mitigate the effects of ethanol in our fuel, but won’t this ethanol also affect the rubber seals in our petrol taps?

I haven’t used a standard petrol tap for many years but I am about to fit a traditional tap to my TV175 preservation.

[Fast n Furious]

The rubber disc seal in most of the taps that I was using did suffer from swelling up and distorting and this was on E5 fuel.
I automatically cut and stamp a new seal from some 1mm thick Viton rubber sheet now before using any new tap.
I suppose you could remove the seal and leave it hanging around in some E10 for a week or so to see if it swells up.

[Knowledge]

Interesting.

Where do you obtain a sheet of viton rubber?

[alex_hughes]

If you don't use a standard petrol tap - what do you use?

[Knowledge]

I build my own long range tanks and fit a motorcycle petrol tap that is connected to the crankcase.

The tap does not flow fuel unless the fluctuation in crankcase (primary) compression is acting upon it.

I do not need a fuel tap lever and my choke has moved up onto the handle bars, which tidies things up around the toolbox door.

Have a look at the SLUK video [youtube-share][https://m.youtube.com/watch?v=3U_SVQWfAII&pp=ygUIc2x1ayAyODM%3D/youtube-share]. It gets a mention on there.

Or search “SLUK 283” in YouTube (54,000 hits)

[Fast n Furious]

It was a few years ago now, so I can't rememeber exactly where I bought this 100x100x1.0mm sample Viton sheet from. I think it was probably from China via Ali-Express.

My TS1 has a vacuum assisted Mikuni DF44-18 fuel pump which is driven from the inlet manifold. This has a delivery average of around 350mL / minute which is more than enough. I fitted this to reduce the possibility of a weak fuel feed into the 35mm TMX carb when the fueltank level gets low.
Other models are availaable which offer a constant delivery pressure but you need a slight mod to return the excess pumped fuel back into the top of the fuel tank.
I wanted to retain the luxury of having a reserve level. (I don't like having to ride with plastic fuel containers strapped to the sprint rack unless absolutely necesary). So the tank is fitted with an OMG fast flow fuel tap which has been modified slightly by oversize drilling the holes in the tap casing a bit more and widening the trough on the disk with a dremmel to improve the flow rate. Got some 5mm thinwall brass tube from a model shop to make a slightly bigger main feed delivery tube into the tap. On reflection, I think this was all a bit unecessary when the fuel supply is assisted by a vac pump, but worth doing on a greedy gravity-fed steed.
Vacuum assisted pumps only offer the required degree of "piece of mind" providing that you use a known quality brand. There's a lot of pattern crap out there. Beware.... these are notorious for their early failure rate.
A new Viton rubber disc seal was cut to size for the tap using my trusty hollow gasket punches and a scalpel.

[gaz_powell]

The only issue i have had was with a Mk1 Scootopia, which swelled even before E10. It was replaced and been fine since.
OMG never had a problem but i do avoid E10 as much ss possible.