MkIII tank and petcock questions

ag12680 · Jul 9, 2015

More time with the New to me Norton and more questions from someone new to the brand.

Both of the petcocks levers broke off and I'm looking to rebuild if the nylon insert can be had. Can't seem to find. If not, what is the the best replacement source for original?

The foam under the tank is disintegrating. Is there a replacement or is it really needed?

Lastly, all my tank rust removal experience is with Japanese bikes. This tank has not been coated inside but appears to have a finish I don't recognize. I've used citric or phosphoric acid with a length of chain/bolts with good results previously. Am I missing something?

Much appreciated..
Andy --

Danno · Jul 9, 2015

I don't believe the petcocks are rebuildable, just replaceable. The foam pad at the rear of the tank tunnel holds the tank off the frame tube. In the front, the tank rests on the rubber donuts, but a the rear, the donuts attach to a padded cross bracket that passes under the frame tube and therefore the tank needs the foam pad in the tunnel for support.

nortriubuell · Jul 9, 2015

As far as fuel petcocks, I would go with "OMG" type. Better than OEM and even better than the "BAP" type IMO. Decent price too. Below is a picture of them on my bike, and a link to fleabay for a set :

... and the fleabay link:

http://www.ebay.com/itm/NEW-Petcock-SET ... 86&vxp=mtr

Hope this helps, cheers.

drp · Jul 9, 2015

You should check out Old Brits, Ella and Fred are great people to deal with. http://www.oldbritts.com

In checking their catalog for the MK III (1975?) it looks like there are two rubber pads and I assume one is for the Roadster and the other for the Interstate (06-2567Gas Tank Pad, Rubber, Thick, 4"x4"x13/16" or 02-6359 Tank Rubber Pad, Thin, 4 5/8"x2 3/16"x1/4"). These are around $5.00 I believe.

Regarding the Petcocks it depends on whether you want the original style or improved ones. I personally prefer the billet ones available from British Bike Connection because they do not leak. I have them on my Triumph and Norton http://www.britishbikeconnection.com/ Look at the custom parts tab.

They are about $69 each but I think they are worth it. You can also buy petcocks that are closer to the original ones from Old Brits or many of the other British motorcycle suppliers.

Dave

jaydee75 · Jul 10, 2015

The original petcocks are rebuildable in that they can be taken apart, but you have to make the parts. I replaced the nylon sealing cones with solid teflon several years ago. It requires a good lathe and some skill, but it can be done.
Jaydee

Deets55 · Jul 10, 2015

ag12680 said:
More time with the New to me Norton and more questions from someone new to the brand.

Both of the petcocks levers broke off and I'm looking to rebuild if the nylon insert can be had. Can't seem to find. If not, what is the the best replacement source for original?

The foam under the tank is disintegrating. Is there a replacement or is it really needed?

Andy,

The Roadster tank requires two foam pads, one in the front and one in the rear plus the rubber washers that go on the front mounting bolts/studs. I recently noticed some chafing in the center of the tunnel so I put in new washers and put a thin form pad (same as the front pad) on the main tube using spray adhesive. I got all my parts from Old Britts.

drp is correct there are two different thicknesses for the rear. The thinner one should be the correct one.

I am using the petcocks that CNW sells and I am very happy with them. They have 3 positions, Off, On, Reserve. I run with them both in the On position. In the reserve position I should have access to all the remaining fuel.

Hope this is helpful

Pete

L.A.B. · Jul 10, 2015

Deets55 said:
drp is correct there are two different thicknesses for the rear. The thinner one should be the correct one.

According to the MkIII parts book diagram, item 9, "06-2567 Rubber, thick (Roadster)" is drawn at the rear, and is the one I would personally want to use at the rear of a Roadster tank.

http://bigdcycle.com/tempbooks/nor/1975.pdf (Group 30)

http://www.nortonmotors.de/ANIL/Norton% ... 030&Part=9 (Item 9).

Deets55 · Jul 11, 2015

L.A.B. said:
Deets55 said:

drp is correct there are two different thicknesses for the rear. The thinner one should be the correct one.

Click to expand...

According to the MkIII parts book diagram, item 9, "06-2567 Rubber, thick (Roadster)" is drawn at the rear, and is the one I would personally want to use at the rear of a Roadster tank.

http://bigdcycle.com/tempbooks/nor/1975.pdf (Group 30)

http://www.nortonmotors.de/ANIL/Norton% ... 030&Part=9 (Item 9).

Les,
Yep you are correct. For some reason I thought there were three different size pads. A thin one up front and two types in the rear. A real thick one for the Interstate tank and a pad that was sized between the thickest and thinnest one for the Roadster. I have to remember to stop relying on my memory.

Pete

P.S I did get that Ace Cafe tee shirt and menu when my son went to London.

Ricochetrider · Jul 11, 2015

I bought a pair of BAP petcocks from the Commando seller on e bay.
Commando specialties, perhaps? .

ag12680 · Jul 15, 2015

Thanks for all the advise. Much appreciated.. Just getting back from a trip and seeing all this.

Wish I did have a lathe and the skills.. Will get with the folks at oldbritts.

I continue to be struck by the differing engineering philosophies of the British, Japanese and Germans.

Thanks again,

Andy --

MkIII tank and petcock questions

ag12680

Danno

nortriubuell

drp

jaydee75

Deets55

L.A.B.

Moderator

Deets55

Ricochetrider

ag12680

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