Please identify this motorbike

[RandomHero91]

This is a photograph of my grandad i would guess around 1946. Please help identify the bike

[33d6]

That’s a tricky one isn’t it. A combination of Box Brownie lens and fashionable baggy trousers of the day neatly eliminate any recognition points.
I’d say mid-late 30’s with the twin filler caps hinting at a combined petrol and oil tank for a total loss lubrication system. That would cut it down a bit. Levis, Ok Supreme, Montgomery. Anything fitted with a JAP engine.
I hope someone knows. I can’t pick it.

[cardan]

My first thought with the twin filler caps was BSA C11, 1939-ish, but I can make out enough different bits and pieces to rule that out. Rear brake inside the back sprocket on the left, decent size front brake on the right, and I fancy I can see a full cradle frame under the engine joining the front down tube. Mmm... tricky. Much easier to identify a British bike from the timing side!

Leon

[R]

So, we have twin petrol caps, a lucas headlamp with ammeter and switch on toppish, and a biggish looking sloper engine
(unless its a v-twin, which I'd doubt - doesn't look solid enough build).
Rear brake inside the rear sprocket.
And whats that circular object in front of the engine, below the horn ?
So its 1930s, and almost certainly British.

At first I'd plump for a Raleigh, but I think the headlamp is later.
Hmmm

[cardan]

And whats that circular object in front of the engine, below the horn ?

No idea! Guess it could be magneto or generator related, or...

The nearly-vertical front down tube on the frame must be a decent identifying feature, but can't think of what it identifies!

Leon

[cardan]

BSA built some lightweight 500cc ohv twins for the army around 1935. Here's one of them - could your grandad's bike be AMP366, and this be the actual bike?

Leon

[cardan]

Some reading:

The photo of AMP366 comes from here https://motorcycletimeline.com/1935-2/ where it was captioned: "Three years after acquiring its first BSA 498cc V-twin for assessment the War Office ordered a lightweight version (hence the undersized fuel tank) but subsequently decided a side-valve single would be more suitable."

Here's a similar model that was for sale (some time ago) https://motorcycles-for-sale.biz/sale.php?id=37628 The model was called the B15 - some interesting comments on "standardisation" that happened on the military models. The tank on the bike in the photo with your grandad is most likely BSA C11; perhaps part of the standardisation process.

Leon

[cardan]

Also worth noting on grandad's bike is the sheet-metal shield that has been fitted in front of the twin down tubes, and presumably turning underneath as a bash plate. The rear stand has been removed and replaced by a long "field stand" behind the rider's left leg. I think these were part of the Ariel WNG design.

Leon

[cardan]

Here's one that sold a couple of days ago at Bonhams. 500 twins are pretty rare and it brought 20,000+ pounds - a very good result for the seller in the current environment. https://cars.bonhams.com/auction/29273/lot/309/the-clive-wood-mbe-collection-1934-bsa-498-hp-j34-15-ohv-twin-wd-frame-no-b15328-engine-no-b15372/

I'd be most interested to learn if the bike in the original photo is AMP366. There are 26,000 combinations of one letter + three digits, so to see two bikes of the same model both with regos ending in ...P366 would be a remarkable coincidence if they were not the same bike. There's a story there somewhere, but unfortunately the original poster seems to have lost interest.

Leon

[Rex]

£20G's for that? It might be a rare bike but it's scrappy resto job at best.

[cardan]

Yep £20k is a lot!! I don't want to own one, but it might be nice (and interesting) to ride. I wonder how far they got the weight down - did you notice the lightening holes in the forged backbone of the frame on AMP366? And the oil tank in the petrol tank in grandad's photo would also save weight. A peppy 500 twin with the weight of a 350? Nice.

Leon