Commando petcock

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Shelby-Right

Shelby-Right

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Does anyone know what seals are in these petcocks , I see Andover have a new tap and washer , but haven't seen a kit , mine will leak,but only sometimes or a wiggle will fix it , and I though once I pull it apart ........... it will take weeks to get a new tap . But if it's just orings it will be something I have. Cheers in advance
 

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If it is the same as the original the moving part has a taper which seals against the taper in the body there is an O ring on the moving part but that is just to stop fuel leaking to the outside. Once they leak the real answer is to replace them. I have tried regrinding them but didn't have much success.

There are some that look the same but use a rubber sleeve to effect a seal and they are hopeless as the rubber swells and then they just pass a dribble of fuel.

The BAP type taps are much better unless you are desperate to maintain originality.
 
If brass, the taper can be restored with grinding paste (as for valve lapping). Put it on the taper and then rotate gently back and forth in the housing to restore the fit.
 
Shelby-Right said:
Does anyone know what seals are in these petcocks , I see Andover have a new tap and washer , but haven't seen a kit , mine will leak,but only sometimes or a wiggle will fix it , and I though once I pull it apart ........... it will take weeks to get a new tap . But if it's just orings it will be something I have. Cheers in advance
Click to expand...

It looks like the typical tubular 'rubber' seal type (on the left in the picture below) with a parallel-sided pin attached to the lever that turns inside the tubular seal and is usually available (in either main or reserve types) from just about all British motorcycle parts suppliers.
Commando petcock


Random examples:
www.classicbikepartscheshire.com

Triumph BSA Petrol Tap Main Chrome Flat Lever Classic Motorcycle 1/4" x 1/4" With Ferrule

Petrol Tap - Universal Chrome flat lever with filter (Main) Thread Type: 1/4' x 1/4' Flat Lever with stainless steel ferrule & nut ready to go. Supplied with New highest quality Ethanol resistant Viton seals excellent quality! OEM: 83-2800
www.classicbikepartscheshire.com www.classicbikepartscheshire.com
www.fasteddiesmotorcyclespares.co.uk

2 x TRIUMPH T120 TR6 PETROL TAPS TRIUMPH BSA MAIN AND RESERVE 1/4 1/4 VITON SEAL

A PAIROF 1/4" X 1/4" BSP VITON SEALED ETHONOL RESISTANT FLAT LEVER WITH BRASS FILTER1 X MAIN TAPAND1 X RESERVE TAPTRIUMPH TR6 T12083-2800 83-280103-1746 03-3155
www.fasteddiesmotorcyclespares.co.uk

Petrol Tap 1/4-1/4" BSP BSA. Norton. Triumph 1 with tube. 1 no tube/Paar | BRITISH Only Austria Fahrzeughandel GmbH

www.vintage-motorcycle.com www.vintage-motorcycle.com

The conical seal type (on the right in the previous picture) that can be lapped has a soft gauze 'sock' type filter instead of the rigid white nylon/plastic frame:

60-4512 Fuel Tap with Indicator Reserve - UK Made - Triumph Petrol Taps - British Motorcycle Parts

www.britishmotorcycleparts.co.nz www.britishmotorcycleparts.co.nz

Both types are available either with or without the indicator plates.

(And the tap in the centre is an original 850 Mk3 type with a nylon/plastic pin/taper that usually broke within a short time as that one has!)
 
Last edited:
Shelby-Right said:
Great , very helpful , maybe that outer oring is crook on mine . Cheers .
Click to expand...

If the pin lugs are chromed then it's more likely to be the tubular seal type especially as you can "wiggle" the lever.

The original brass cone taps didn't have an O-ring as the one on the right in my previous picture (Edit: and below) doesn't.
Edit:
Commando petcock
 
Last edited:
Fast Eddie said:
Those tubular seal types should be banned!
As stated already, the rubber can swell and virtually block off the fuel.
This has very real dangers regarding fuel starvation at high rpm and resultant engine damage.
Click to expand...
I agree. Tried them a couple of decades ago with poor result.
 
I have renovated a number of these over the years. It costs next to nothing, but time, an o-ring, and a bit of abrasive paste. They work for a while, but eventually they start binding to the point that you are reaching for a small wrench to open and close them, then the skinny little handle starts bending.
I read that the removal of lead in the fuel leads to the binding?
Fixing them is a waste of time if you plan on riding the bike.
 
Last edited:
Cheers , maybe my cap full of marine two stroke in a tank full will help on the lube side .
 
I use the Paoli type 90 degree ones from cNw on my Commando and Paoli straight ones on my T140 and they work perfectly.

www.tricor-andy.com

PETROL TAP PAOLI RESERVE | Tricor Andy

www.tricor-andy.com www.tricor-andy.com

When I want ‘traditional’ taps I get them from Andy Molnar, I figure that if they’re good enough to feed a top spec Manx Norton at WOT they’ll be fine for my needs!
 
Fast Eddie said:
I use the Paoli type 90 degree ones from cNw on my Commando and Paoli straight ones on my T140 and they work perfectly.

www.tricor-andy.com

PETROL TAP PAOLI RESERVE | Tricor Andy

www.tricor-andy.com www.tricor-andy.com

When I want ‘traditional’ taps I get them from Andy Molnar, I figure that if they’re good enough to feed a top spec Manx Norton at WOT they’ll be fine for my needs!
Click to expand...
I tested the Paoli BAPs and they flow about half as much as the new AN ones IIRC.

Petcock reserve and replacement question

I just got some BAPs for the roadster after the previous (possible knock-off BAP copies?) got nearly too stiff to turn. I now use the "two reserve taps" setup, as I hate trapped fuel in what is a small tank. This will give around 7-11 gentle miles reserve until you are pushing, depending on how...
www.accessnorton.com www.accessnorton.com
 
L.A.B. said:
Running a drill bit through them clears the restriction.
Click to expand...
I took them apart and used a gasket hole punch on mine. Worked, but then replaced them with the ball valve style taps on the Combat. The purple bike still has this style.
 
These are made from domestic heating gas taps, not gasoline taps. The are 1/4" ball valves and pass more fuel than the standard petrol tap / petcock. They can be bought with the correct 1/4 BSPP thread.

I make them up myself and have them on my 4 bikes. 3 race bikes with no need for reserve, but I made a main and reserve tap pair for my road bike.

I have a tap to thread them for the filters. I seal them to the tank boss with dowty washers. I rotate the tap lever to point the way I prefer, flange toward the tank. They can be used the other way round if you are anal about using a lock nut and aligning the tap lever to face outwards. Since I use Mikunis that don't dribble much past the needle valve, I only use the taps at the start and finish of a day's use, so don't find it too inconvenient to reach round.

Idea used before me by a Norton specialist we all know of, I actually bought my first pair from him, and by quite a few two stroke racers I know, at least one of whom was a plumber.

I keep a spare pair in the race day tool box!


Commando petcock
 
Hi all,
does one of the standard taps on a Roadster have a stand pipe in it to provide the reserve or is the reserve fuel provided when the level in the tank is sufficiently low that it cannot flow from one side to the other, because of the internal hump in the tank where it fits over the frame.
I hope this makes sense
al
 
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