This petrol tank was on ebay a couple of weeks ago,its back on again now (ebay item no 334201679733).It has the cut out on the right side which has been welded to make it look like a normal tank again,the petrol filler cap opens to the left side of the tank (to miss filter??) instead of to the rear,also one of the tank knee rubbers is similar/same lighter colour as a tank that Kieth Chandler found in the 70s,also it looks as if there is some kind of formation sign under the black paint but on top of the original khaki paint.

Steve, did the tank look to you as if the rear corner was a factory mod ? I has often been suggested that BSA used up wartime Vokes-compatible tanks by welding a tail back on. Norton were odd of course as despite having invented the Vokes cutaway, their late-war Vokes-equipped bikes didn't have it. The side-opening filler is indeed another feature that appears on the air filter bikes.

I think that badge you're seeing is simply the 1950s round Norton logo, or a variation on it.



Could the pale rubber knee grips be some sort of synthetic rubber compound, perhaps that was black-finished originally ?

Hi Rik, I wouldn't know if it was done at the factory, I suppose you would have to compare it to other similar modified tanks, I think you're right about the transfers, but it does look like these have been put on top of the original khaki, the knee rubbers are a bit of a mystery, would probably need to handle it to see what it's made from.

The side opening of the petrol filler cap would suggest that it was for a tank that could carry the tank top air filter. As for the light coloured knee grip - the one I have on my RAF 16H tank is rubber and not as far as I am aware a synthetic compound.

I have seen period photos of a SWD Big 4 with a tank top air cleaner but never seen a SWD Big 4 fuel tank with a cutaway to accept one.

Trust this helps

email (option): keithchandler@clistandchandler.co.uk

Tank has sold now ,dont know if any one on the forum bought it.