TAB II Alloy Tank #3

Stephen_Spencer said:
Short tank first test ride today. Bike was faultless - tank not quite so!

I filled up prior to setting off, making sure not to overfill as TAB recommend. 50km in I stopped for a coffee and noticed fuel dripping down the RHS of the tank. Cleaned it off and made the return journey. 100+Km total and still losing fuel from the cap at the end of the ride - so definitely not an overfill situation.

Pretty sure it’s coming via the cap itself, so maybe vapourising and forcing past the diaphragm because the vent hole is blocked? Or the diaphragm nut needs to be adjusted (tightened) slightly to increase the spring pressure between diaphragm and tank closing face?

TAB warn of slight leakage because of the Monza style of cap as its requirement to ‘breathe’, especially when topped off. Hoping this is not the norm for anyone who wishes to fit decals or paint the tank.

I’m a Monza virgin - anybody experienced this with their TAB tank, or other - Ideas?

Should’ve fitted the decals after the test ride - right one is ruined! DOH!

Rhymes with ‘clucking bell’! :rolleyes:

View attachment 109747
View attachment 109748
Click to expand...
Is that cap welded to the tank or is it a threaded on cap?
My Norton aluminum tank monza cap is threaded on. I used a same sized flat o-ring between the cap ( think of a o-ring from a spin on oil filter).

This stopping my fuel seeping and also allowed me to tighten the cap and align it to my liking.
 
Voodooo said:
Is that cap welded to the tank or is it a threaded on cap?
My Norton aluminum tank monza cap is threaded on. I used a same sized flat o-ring between the cap ( think of a o-ring from a spin on oil filter).

This stopping my fuel seeping and also allowed me to tighten the cap and align it to my liking.
Click to expand...
His terminology is a bit vague Voodooo, but my understanding is that no it’s not threaded. The cap ring (which he manufacturers) is welded to the tank. The cap itself is positioned, by interference fit. over the cap ring and secured/sealed with a chemical metal two part epoxy.

I don’t believe it is leaking via interface between tank/ring or ring/cap. Pretty sure it’s breaching the seal or slopping straight out of the vent.
 
Stephen_Spencer said:
His terminology is a bit vague Voodooo, but my understanding is that no it’s not threaded. The cap ring (which he manufacturers) is welded to the tank. The cap itself is positioned, by interference fit. over the cap ring and secured/sealed with a chemical metal two part epoxy.

I don’t believe it is leaking via interface between tank/ring or ring/cap. Pretty sure it’s breaching the seal or slopping straight out of the vent.
Click to expand...
Sounds like you need less fuel in the tank. Or, another / better tighter seal.

Too tight, and the cap will be hard to close, and it’ll put more pressure and wear on the latch and hinge pin.
 
Voodooo said:
Sounds like you need less fuel in the tank. Or, another / better tighter seal.

Too tight, and the cap will be hard to close, and it’ll put more pressure and wear on the latch and hinge pin.
Click to expand...
Agreed Voodoo, but less fuel doesn’t work - it was still leaking at about 60-70% full and let’s face it, the 961 doesn’t have the best range to start with.

I’m getting advice from the cap manufacturer (via TAB) about adjustment of the cap: how much to apply; line up of vent holes between pressure plate, rubber washer and backing plate; and whether the adjustment nut is loctited - don’t want the whole assembly landing inside the tank. It’ll definitely leak then:oops:!
 
No luck with the cap - it leaks quite badly regardless of how it’s adjusted. It is breaching the sealing face when fuel washes/tumbles over that area.

I can actually reproduce the leak by pulling the bike firmly to the right with the bars, whilst stood to the RHS of the machine.

Difficult to see why this is occurring. Most likely:

- Insufficient spring pressure, regardless of setting - incorrect spring length (17 mm)/weight?

- Cap-ring mating surface is ridged from the machining process, providing a poor sealing surface?

- Sealing washer is inadequate in some way?

- Cap to ring interface is misaligned for some reason - unlikely.
Click to expand...

TAB II Alloy Tank #3


TAB II Alloy Tank #3

The individual components look OK.

Awaiting a response from TAB - they suggested sending a new cap lid so I’m guessing that’s the next step.

Gives me time to get the seat recovered while I wait I suppose! Also answers the wife’s usual question “why‘d‘ya need multiple bikes when you only have one ass!? 👍

TAB II Alloy Tank #3
 
Stephen_Spencer said:
No luck with the cap - it leaks quite badly regardless of how it’s adjusted. It is breaching the sealing face when fuel washes/tumbles over that area.

I can actually reproduce the leak by pulling the bike firmly to the right with the bars, whilst stood to the RHS of the machine.



View attachment 109928

View attachment 109929

The individual components look OK.

Awaiting a response from TAB - they suggested sending a new cap lid so I’m guessing that’s the next step.

Gives me time to get the seat recovered while I wait I suppose! Also answers the wife’s usual question “why‘d‘ya need multiple bikes when you only have one ass!? 👍

View attachment 109930
Click to expand...
Is the rubber seal going inside the filler neck instead of sealing on the top of the lip?

Also is it possible to be leaking here where the seal wouldn’t make much contact?
 

Attachments

  • TAB II Alloy Tank #3
    IMG_3257.jpeg
    1.1 MB · Views: 70
Voodooo said:
Is the rubber seal going inside the filler neck instead of sealing on the top of the lip?

Also is it possible to be leaking here where the seal wouldn’t make much contact?
Click to expand...
The rubber washer was rather hard, so I swapped it out for a silicon washer - both are toilet cistern washers by the way. This is sealing much better although the silicon is not likely to survive very well in contact with fuel.

Haven’t road tested it yet as it is now apparent that it is also leaking from the weld between Cap-Ring and tank. Awaiting guidance on a decent sealant. Just got unlucky it seems.

TAB II Alloy Tank #3TAB II Alloy Tank #3

TAB II Alloy Tank #3
 
Bummer about the weld Steve, but coincidentally there was a thread about a similar issue on the classic forum a few weeks ago...

Aluminum gas tank filler neck repair

I have an aluminum fastback tank I got from walridge over 10 years ago.The fuel has been leaking from under the quick fill filler cap were it is fastened to the tank.There was some kind of brown filler they used to seal it when made .It has been flaking off now when I fill it anywere near the...
www.accessnorton.com www.accessnorton.com

Regarding the leaking top seal, I reckon you could limit the amount of fuel sloshing up there by fitting an inner cap (think bathplug). The ring of weld would stop it dropping into the tank.
 
cliffa said:
Bummer about the weld Steve, but coincidentally there was a thread about a similar issue on the classic forum a few weeks ago...

Aluminum gas tank filler neck repair

I have an aluminum fastback tank I got from walridge over 10 years ago.The fuel has been leaking from under the quick fill filler cap were it is fastened to the tank.There was some kind of brown filler they used to seal it when made .It has been flaking off now when I fill it anywere near the...
www.accessnorton.com www.accessnorton.com

Regarding the leaking top seal, I reckon you could limit the amount of fuel sloshing up there by fitting an inner cap (think bathplug). The ring of weld would stop it dropping into the tank.
Click to expand...
Thanks Cliff.

Thats very useful - JB weld it is. Don’t use ethanol fuel options anyway.

I can create a leak through the weld, by surging the fuel (moving the bike sideways) and then blow fuel down the outside of the tank from the inside of the filler neck, using a puffer bottle! So there’s definitely a hole or holes in the Ring-Cap to tank weld. Unfortunate but no big deal!

I’ll take a look for an inner cap - that may be pretty useful 👍!
 
Stephen_Spencer said:
Thanks Cliff.

Thats very useful - JB weld it is. Don’t use ethanol fuel options anyway.

I can create a leak through the weld, by surging the fuel (moving the bike sideways) and then blow fuel down the outside of the tank from the inside of the filler neck, using a puffer bottle! So there’s definitely a hole or holes in the Ring-Cap to tank weld. Unfortunate but no big deal!

I’ll take a look for an inner cap - that may be pretty useful 👍!
Click to expand...
If you get stuck, let me know the diameter of the inside of the neck and I could knock something on the lathe.
 
Stephen_Spencer said:
No luck with the cap - it leaks quite badly regardless of how it’s adjusted. It is breaching the sealing face when fuel washes/tumbles over that area.

I can actually reproduce the leak by pulling the bike firmly to the right with the bars, whilst stood to the RHS of the machine.



View attachment 109928

View attachment 109929

The individual components look OK.

Awaiting a response from TAB - they suggested sending a new cap lid so I’m guessing that’s the next step.

Gives me time to get the seat recovered while I wait I suppose! Also answers the wife’s usual question “why‘d‘ya need multiple bikes when you only have one ass!? 👍

View attachment 109930
Click to expand...
With the weld leaking , you may want to send it back to TAB II and get it repaired /tested this time ?? Now , is it the weld or the JB weld joint leaking ?
 
TonyA said:
With the weld leaking , you may want to send it back to TAB II and get it repaired /tested this time ?? Now , is it the weld or the JB weld joint leaking ?
Click to expand...
JB Weld Original is the recommendation Tony.

Thought about sending the tank back for a nano-second. Really don’t want to be screwing around swapping fuel pumps back over and shipping it back across the globe, for what might be a simple repair. If I can’t fix it easily and it keeps leaking I’ll ship it.
 
Breach in the tank weld fixed with a short run of JB Weld - no problem.

Still a minor leak from the cap if I fill to above 1” from the top of the battery storage section. TAB have been very responsive - new cap on the way. They’ve thrown in some new decals also which I didn’t ask for - good on em’.

My Monza Cap is further to the RHS than any other they produced - wondering whether that’s opened it up to the perfect position for fuel wash over the cap aperture on RH bends and it’s simply flowing through the vent. I’ll know when the new cap is fitted. Also more difficult to weld.

For future reference the cap rubber washer is a standard cistern rubber washer. The newer silicon type seals better, but is destroyed by the fuel within a few days - do not use.

On reflection, a centrally mounted cap may be a better option for those planning to order.

IMG_8701.jpeg

IMG_8679.jpeg
 
Last edited:
  • Like
Reactions: MAK
I wonder if a Monza style cap like the new Triumphs have is an option for TAB to use on these tanks?
This has an inner screw-in cap below the actual Monza cap, which does the sealing duties for the Monza cap.
The Triumph tanks must have a different venting layout, so don't know if this would work on a TAB tank.
But worth asking the question, no?
 
BritTwit said:
I wonder if a Monza style cap like the new Triumphs have is an option for TAB to use on these tanks?
This has an inner screw-in cap below the actual Monza cap, which does the sealing duties for the Monza cap.
The Triumph tanks must have a different venting layout, so don't know if this would work on a TAB tank.
But worth asking the question, no?
Click to expand...
No doubt the pseudo-Monza would seal better BT, for those that want the look without the hassle - the net is full of tales of leaking traditional Monza Caps.

Don’t think it would be of interest to TAB though (or me for that matter) as they pride themselves on producing truly authentic product, using traditional methods.

That said, I’m gonna fit a non-authentic tank strap at some stage - cos I like the look and ya gotta protect the tank from the dreaded zipper. This beauty would scratch with the passing glance of a partly inflated condom.

Used to think the silver tank on black bike looked disjointed. Not now - it has grooooown on me big time! Lovin the appearance although it’s made it even more difficult to get away from biker haunts😁!
 
Stephen_Spencer said:
So, a bit of information for those looking to have decals produced for their TAB tank. My plan was to have my chosen scheme produced as a decal, so I could run it for a while to make sure it worked before getting it painted.

The decal firm I hired produce great stuff, although mainly for dirt bikes - they came recommended. However, they had the following issues:

- they initially had difficulty getting a smooth set of curves; I could see the vector points.
- eventually got a relatively smooth set of curves but had difficulty where the pinstripes intersect to a point. Before correcting this;
- they did a dry run with a test decal and could not get the decal to adopt the steep curve toward the front of the Norton tank, without creasing. Despite using heat etc.

Got a call this morning to say they couldn’t complete the task - C’est la vie!

I have the AI & PSD files so I’m gonna try and complete the graphic myself and find a local wrapping firm. They should have no problem with a wrap rather than a much thicker decal.

Failing that (and eventually anyway) I’ll get it painted. Until then I put the logo decal on - looks just OK to me.

The takeaway then - choose your decal firm well. Ideally they would have experience doing a wider variety of jobs, beyond the flat profile stuff prevalent on dirt bikes. Challenge them from the outset on whether they can apply your chosen decal to the significant curved profile present at the front of the TAB tank.

When I’ve finished the decals I’ll put the files on the resources page should anyone want to use them.

View attachment 109701

View attachment 109700
Click to expand...
Hi Steve , Where are you getting your throttle wheel cover from ? I would like one like that. Is Cliffa making them ?
 
You must log in or register to reply here.
Back
Top