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Easily identified as the engine number ran vertically down the rear of the gearbox in the last of the AAA series, AAA****A whereas they then moved to the postwar engine numbering system found on a raised boss on the right hand side gearbox end plate...   

There must be a bit of overlap: here's a "postwar" number running vertically down the back of the gearbox, on a very original postwar Acme, maybe 1947-ish. 351/1287 is a pretty low postwar number, so I assume they were on the back for a while before moving to the end plate of the gb?

Leon

That head has so few fins! Good luck with the start-up.

Leon

Just pre-war or just post-war is often a difficult call. There's a "1914" single cylinder, shaft drive FN current for sale here in South Australia - it's a lovely bike but I strongly suspect it's actually 1920-build. For FN the war was pretty clear cut: Liege was overrun, the FN factory was taken over for German war work and there were no motorcycles made from 1914 until 1920. The first bikes of 1920 were pretty-much 1914 models.

Not sure what happened at Excelsior, but they did manage to build 5000+ Welbikes during the war. The Excelsior/Waratah in question has some pre-war-ish features, like the gear change and the bolt-on rear subframe, but a hint of postwar with the headlamp and (maybe) the front fork. The other well-known Australian bike of the era was the Acme (much more Australian-made than the Waratah), and it used the Sackville pressed-steel fork pre-war and the Webb post-war, so maybe there is an element of that here. Some Acmes for the early war years (1940-ish) used the "modern" "bullet" Villiers headlamp rather than the old "tobacco tin".

So very hard indeed to spot differences between a 1939 model bike and the first bikes delivered in 1946, when getting stuff out the door was more important than adhering to a catalogue specification. The 1946 Waratahs and the 1946 Excelsiors may have differed: if there were left-over pre-war parts in the factory I know where I'd send them! Numbers will give more clues.

Leon

"One other thing he suggested though was taking the 1/8" BSP 28tpi oil union and running a 3/8" BSC 26tpi Die down it."

Please don't.

Re the backlash in the drive train from the crank to the magneto: this sort of thing is pretty typical and doesn't matter too much. Because the engine is driving forwards at all important times, the gears are all stressed in one direction, and this guides how the timing (of valves and magneto) is set. Decent descriptions of how to time an engine will always mention that the engine should be turning forwards.

Leon

Anyway, I wouldn't mind the frame number as every new number helps to better understand these early Australian bikes.

Weirdly I was working at my bench this afternoon when I noticed a banjo fitting on the (very messy!) windowsill. I measured it: 1/8 BSP on the screw-in end and 3/8 BSCy on the nut end.

I have an Australian-made bike with a Spacke De Luxe engine, made in the USA. One of the fittings the oil pump is 1/8" NPS, which is major diameter 0.405", 27 tpi.

So 0.375", 0.383", 0.405"... 26, 28, 27 tpi... you've got to love a good thread.

Leon

We live in a golden age of information.

This is how to squeeze a 4 1/4 Precision into this frame - pretty brutal, just bend that down tube a bit... The engine is the 1912-only model, quite different to the later Big Four engines. The bike is a Melbourne-built Morton.

Looking closer at the surviving frame, the engine plates with it are the Precision type, rather than the Fafnir type (which also picked up on a lug high on the crankcase near the back of the cylinder).

Frame number tells all.

Leon