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Fuel Tap Troubles
Received 14 May 2020
By Mark Noel
I thought that I would tap into other folk's experiences with taps! Almost every motorcycle that I have owned has suffered at some stage from a leaking petrol tap. It seems that both older people and older motorcycles often suffer from dribbling and I have invested time and effort over the years in trying to solve this problem: for the bikes that is, not me!
My earliest steeds were by BSA, Norton and Ariel, and like most British bikes of the era they were fitted with the hopeless Ewarts fuel tap. These were of a simple plunger type - pull out for on, push in for off, with sealing supposedly accomplished by a simple cork insert. These seals inevitably disintegrated resulting in a permanently flooded carburettor float bowl and weeping over the engine and garage floor.
My Suzuki GN125 had a tap which internally comprised a plastic cone with ports for on and reserve, which revolved in an aluminium housing machined with a matching tapered recess. However, after only 8000 miles this also leaked and was replaced with genuine Suzuki spare which again leaked after less than a year. I tried to solve this by lapping the cone into the recess with metal polish to get a better seal but the dribbles were only reduced not abated.
Coming up to date I now own a new Herald 250 Classic which is a Chinese reproduction of the gorgeous Suzuki TU250X. Almost from day one the tap leaked, staining the engine paint and flooding the carburettor. Like many modern units the tap is a face seal design with a ported disc rotating against a nitrile flange with openings for On and Reserve. A wave washer exerts force to maximise the disc-washer seal and an O ring is also fitted to prevent leakage outside the housing. These parts are shown in the photograph here.
I discovered that the leak was caused by the disc face not being flat (unfinished diecast) and by the O ring having expanded and crumpled inside the housing. Clearly it was not made of fuel-proof Nitrile, but was some type of rubber that had swollen and moved out of place. Poor quality from you-know-where!
My hunt for a decent replacement took me to ebay from where I obtained an aftermarket copy of a Suzuki tap which was again found to have a faulty design and poorly fitted face seal as shown in the second picture. Another serious issue was my discovery that the ports for On and Reserve were reversed which might prove fatal on the road when you depend on the fact that you have some miles left in the tank! Poor quality control again. The lesson here is to check that a replacement aftermarket part works as you would expect.
In the garage I have a nearly-new Jawa 350 Classic where the design and all the parts are brilliant, including the fuel tap which has a smooth dribble-free action (see photograph).
It is of all metal construction but will be difficult to adapt to fit my Herald 250. So the hunt continues for a faultless petrol tap, or 'petcock' as the Americans like to call it. They also say 'fawcet' when they mean tap, and I say 'tap' when I thread a hole. Confusing innit?
It would be interesting to hear other peoples' experience of this problem which has caused me and my bikes to weep many times over the years!
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Reader's Comments
Ren - The Ed¹ said :-
Having put a large number of miles onto various questionable motorcycles I have never yet had a fuel tap issue!
Either...
I've almost always owned Hondas and they can make fuel taps
or...
Mark is one of them there diligent and careful type what actually use a fuel tap when they park up. For me they were only used when taking the tank off.
21/05/2020 15:50:10 UTC
Bill said :-
My Honda crf has the same 2 bolt fitting,if you measure the centres and hole diameter I could check the dimensions for you, the OEM tap has been trouble free since 2004. So could be worth buying genuine Honda to use on your Herald.
21/05/2020 16:08:41 UTC
Upt'North said :-
The last bike I had with a fuel tap was a CB750. It was 30 years old when I sold it and it worked just fine and dandy. Not a dribble in sight, well from the bike anyhows.
Let some kind sole on here measure there Japanese fuel taps for you and buy one from a breakers. I bet they're cheap because they never go wrong.
I certainly wouldn't buy another cheapo one, they seem to be both cheap and nasty. Although the Japanese bike taps are probably made in China anyway.
Upt'North.
21/05/2020 18:11:53 UTC
nab301 said :-
If you look under any of the parts fiches eg Fowlers , they actually list fuel taps for the TU as special order or more importantly they don't list them as NLA, between 40 and 80 euro though. The bandit fuel tap looks similar but is vacuum operated, easy enough to sort and in any case it has a "prime" setting and would probably be available second hand.
Fuel tap repair kits are available from Wemoto although I know the tap casting is a problem on yours.
https://www.wemoto.com/bikes/suzuki/tu_250_xy/00...
21/05/2020 21:06:03 UTC
Mark Noel said :-
Thanks guys for your helpful suggestions. 40 to 80 Euros is a bit steep for a fuel tap. For the time being I have skimmed and polished the ally mating face of the Herald tap and replaced the O ring with a proper nitrile one from my box of bits, and so far, so good, with no leaks. If the problem persists then I could try making a tap out of brass - a bit of lathe and milling work, then lapping for a atomic fit.
22/05/2020 10:35:45 UTC
Dave (Leicester) said :-
I am 63, and I do occasionally dribble. My bike is a 1963 Royal Enfield Constellation, which I have owned since I was 19.
After many years of being at the back of the garage / shed etc, I finally got it back on the road in 2020, and it has given me miles of trouble free riding since. One issue I've had is with the petrol tap.
I replaced the original cork seal tap with a cheapish alternative from Hitchcocks (Enfield place). This leaked, then broke.
The next tap was a very smart looking brass affair with a smooth lever action (again from Hitchcocks), which had an internal taper arrangement. No seals.. Just relying on the accurate machining of the taper. It leaked. I tried bedding it in. Still leaked.
3rd tap (still on) is a chrome push button type, with a top lever for reserve. It's been better, but I have to remember to turn off the fuel when storing in our covered side passage, or you can small it from the kitchen.
It has recently got worse. There is a permanent dewdrop on the loop of the petrol line as it drips on to the engine.
I need a petrol tap that reliably seals. Any suggestions.
I use 5% ethanol lead-free fuel
Thanks.. Dave.
06/03/2024 12:48:52 UTC
Ian Soady¹ said :-
Hi Dave.
The ones I use on my Norton ES2 are the BAP pattern type like the ones in the link. They're cheap and don't leak but don't look entirely original. But who cares about that?
Oh and welcome to the group. Never had a Connie but I rode a Bullet in pre-65 trials for a number of years, and used a Norton Commando for long distance touring up till the mid-2000s (my mid-60s....)
https://www.classicbikeshop.co.uk/triumph-t120-t140-bap-petrol-tap.html...
06/03/2024 15:27:38 UTC
nab301 said :-
I used a Hitchcocks 147022 tap to replace the OE one which fell apart on my '03 Bullet 65 which has been fine since 2018 ( time flies..) Not sure if suitable thread wise or if it would flow enough for the Connie.
Nigel
06/03/2024 16:05:34 UTC
Dave (Leicester) said :-
Thank you both.. Very useful.
I'll check out both taps, make a decision and let you know how I get on.. ?
Here's an old one from the 80s.
06/03/2024 19:56:03 UTC
Dave (Leicester) said :-
.. and a recent photo.
I use it all the time. It's wonderful to have it on the road again.
Thanks again.
06/03/2024 20:13:36 UTC
Ren - The Ed¹ said :-
Blimey! And I thought I kept my bikes for a long time. Hi Dave (Leicester), great pictures.
06/03/2024 20:50:10 UTC
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