After market petcocks

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N0rt0nelectr@

N0rt0nelectr@

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I had a most interesting experience today. I was out for a ride and went over to Harbor Freight to look for an inexpensive tool. Pulled into the parking lot and went to shut off the fuel and it was pouring out of the petcock. A serious WTF. The petcock had broken off just above the jam nut, felt a bit like the little Dutch boy trying hold back the water with his finger, but in my case it was 5+ gallons of premium fuel. I was very lucky and a couple of guys stopped to help and one even bought a oil pan and a 5 gallon bucket. Bless his heart! Almost filled the bucket before it stopped draining. I was able to remove the end of the petcock from the tank and with the seal removed I was able to reinstall the petcock which still had a leak just not as bad. Got home a re-drained the tank and gave the petcock a good look over. It looks like it had been cracked for sometime but why. Well I do try and keep the petcocks facing out and will tighten them to keep them there. So, maybe I started the damage tightening up the jam nut?
I did dig out a few old British made Ewarts Petcocks and just by feel it seems like they are heavier than the aftermarket ones you find on Ebay. Tried to rebuild one of the old ones but the o-ring was hard and I can't find one locally that is correct.
Here are a few pictures of what I found.
John in Texas
 

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Both of mine have failed over the years. They have both been swapped out for BAP taps and haven't had a problem since.
 
What a bastard!!
You're very lucky to have some very helpful people nearby.
I wonder if anyone makes them with rolled, rather than cut, threads?
The roughness of yours, I'm sure, contributed to its demise.
 
I wish Pingle made a fuel tap with 1/2" BSP threads. Pingle taps are the best ethanol proof taps my research has found.

I talked with a guy at Pingle about this. He said they get a lot of inquiries, but as yet no decision to make them with BSP threads.

They make a tap with 1/4" NPT, which is close to 1/2" BSP. There are three options to use a 1/4 NPT in our Brit tanks:

1) jam the 1/4 NPT into the 1/2 BSP hole until it is tight. Perhaps with Teflon tape it will not leak.
2) run a 1/4 NPT tap into the 1/2 BSP hole. OUCH! This is irreversible.
3) obtain an adapter fitting ..... 1/2 BSP male by 1/4 NPT female. This will change the stand pipe level if you are dealing with a Main/Reserve fuel tap.

Slick
 
Does anyone know what size the o-ring is on the original petcocks? I picked up a few at a local NAPA parts store but they don't seal very well so it is back to the drawing board.
John in Texas
 
texasSlick said:
I wish Pingle made a fuel tap with 1/2" BSP threads. Pingle taps are the best ethanol proof taps my research has found.

I talked with a guy at Pingle about this. He said they get a lot of inquiries, but as yet no decision to make them with BSP threads.

They make a tap with 1/4" NPT, which is close to 1/2" BSP. There are three options to use a 1/4 NPT in our Brit tanks:

1) jam the 1/4 NPT into the 1/2 BSP hole until it is tight. Perhaps with Teflon tape it will not leak.
2) run a 1/4 NPT tap into the 1/2 BSP hole. OUCH! This is irreversible.
3) obtain an adapter fitting ..... 1/2 BSP male by 1/4 NPT female. This will change the stand pipe level if you are dealing with a Main/Reserve fuel tap.

Slick
Click to expand...
I use Pingle's not sure how I did it.Might have been option #1
 
I think the difference between BSP and NSP is the pitch of the thread. The sizing is the same between standards, but is weird as it is different to what you would measure. Like if you measured a 3/8ths hole you need a 1/4 item (example only) Info is on the inter web.
 
N0rt0nelectr@ said:
Does anyone know what size the o-ring is on the original petcocks? I picked up a few at a local NAPA parts store but they don't seal very well so it is back to the drawing board.
John in Texas
Click to expand...

The fluorosilicone blue O rings are both gasoline and ethanol proof.

You can get specialty O rings in small quantities from

http://www.hddistributors.com
Metricseals.com

Sorry dunno about the size in your tap ..... If you snail mail me an old one, I will compare with a size chart I have.

Slick
 
Last edited:
L.A.B. said:
Dimensons, thread form and pitch are different between BSP and "NSP" (NPS? = National Pipe Straight).


https://en.wikipedia.org/wiki/British_Standard_Pipe

https://en.wikipedia.org/wiki/National_pipe_thread

https://www.buyfittingsonline.com/pages/npt-vs-nps-vs-nptf-thread-connections-the-difference.html

https://britishfasteners.com/threads/bsp.html
Click to expand...

To be perfectly clear, the NPT and BSP(P) are different in size, pitch, and thread form but close enough that a few turns of a male NPT into a female BSP(P) can be made and hopefully seal. I do not care to have this bodge on my bike, but I offered it up in Reply #4 as an option for those desparate to have a really good fuel tap.

Slick
 
I have run a 3/8" BSP 19 TPI die over a 3/8" NPS 18 TPI threaded tap and it works. Not sure if it would work on the smaller 1/4" but it's the same 1 tpi difference.
 
I beg to differ. I have 2 BAP petrol taps that broke in exactly the same way as the original poster.
 
johnny Lagdon said:
I beg to differ. I have 2 BAP petrol taps that broke in exactly the same way as the original poster.
Click to expand...
I broke a BAP tap in the same place and in the same way, but now have them on several machines because they are OK if fitted more carefully and because they don't leak.
 
I’ve not broken a Bap but I have had them seize solid and worse, I had a pair that hardly flowed more than a dribble, if I’d put them on the bike I was intending to (988cc BSA R3 motor) the resultant fuel starvation wudda wrecked the motor!

Then I’ve had several cheapo pattern taps with rubber cylindrical seals swell to the point of almost cutting off fuel.

So I’ve become a bit paranoid when it comes to fuel taps. I often use racing taps from Andy Molnar and they’re good. But the cNw ones have the advantage of having a reserve, and they’re a neat installation.

Of course, if one really tried hard enough, one could also buy cheaper pattern versions of the cNw taps and continue to enjoy the above mentioned issues !!
 
Ive had BAP taps break off as well. But truth is maybe they were fake clones. Those CNW taps are very reasonably priced and I doubt Matt would sell anything suspect.
Recently found this:
https://tinyurl.com/y2ntrfkl
Read through it maybe of use.
May I note that one of the problems is the top threads are actually rather too short especially after you put on the nut and a sealing washer. A good
quality half nut might help here.
 
Onder said:
Ive had BAP taps break off as well. But truth is maybe they were fake clones. Those CNW taps are very reasonably priced and I doubt Matt would sell anything suspect.
Recently found this:
https://tinyurl.com/y2ntrfkl
Read through it maybe of use.
May I note that one of the problems is the top threads are actually rather too short especially after you put on the nut and a sealing washer. A good
quality half nut might help here.
Click to expand...

They look like the same taps that Molnar sells for racing Manxes. They’re good taps. No reserve though.
 
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