classic motorcycle forum

Is it sucking in false air through the bronze bushings on the crankshaft?

It will if the main shafts or the bushes are worn: the shafts and bushes need to be round with only a thou or two clearance (say 0.025-0.05 mm). You definitely should not feel any movement if you grab the flywheel and try to move it up and down. If it clunks you're in trouble! The other place that wear occurs in early two strokes is in the bore: not so much up the top (as it is in four strokes) but above and below the ports where the rings jump across. And the rings, of course.

If these parts are worn the bike will probably still run, but will get hot an bothered when riding. If you've got good compression - it really should be quite "sharp" as you kick it over - then wear is probably not the problem at the moment.

Leon

Thanks!

What about the positioning of the piston?
Is this the right way?

You are looking at the left side of the engine as you can also see the “L” on the case.

Yes "maker" is good, or even "builder". Both are probably more accurate than "manufacturer". "Assembler" is a bit special, and in my mind I keep this for those who opened the crate and literally put the parts together. There was a bit of this in Australia in the early days: I suspect the Sun Villiers in veteran years is a good example. Most Australian makers/builders started with imported lugs and parts, and local "vision", and went from there.

Rims either side of the WW2 years is an interesting topic! It turns out that bicycle and motorcycle rims were on the list of controlled imports and were probably not available from, say, 1940 until January 1946 when they were removed from the list. I recall Malvern Star had to massively retool to keep bicycle production going during the war. Anyway, here are some extracts referring to imports of rims (and engines, hubs, and other unclassified parts) after the ban was lifted. 70 bundles of motorcycle wheel rims!

I wonder if the pause in Acme production between 1941 and 1947 was due to shortage of items like rims.

Leon

Does this particular carb have a tickler mechanism.
Nothing visible in the pics.
But could be t'other side.

Or, can that air cleaner (?) be choked.
Even by putting the palm of your hand over something strategic.

Agree, gravity fed fuel strainers are a peril.
Not much gravity in that short distance !

It’s a fine line between ‘manufacture’ and ‘assemble’. Acme erected their own frame. Who made the tubing? Who made the lugs? I would expect Australian made tubing, but what about the lugs? Did buying the Webb forks include the headstock lug? I don’t know.
What about the wheels? The hubs were imported but what about the spokes and rims? I would expect spokes to be made locally but what about the rims? Dunlop were popping them out by the gazillion. Could local manufacture compete given the economies of scale?
So it goes on.
What Bennet & Wood did was no different from many other small motorcycle factories of the time. Lots of proprietary parts but their own vision. I’ll accept ‘maker’.

Last thing. The prewar Acme silencer was merely a Coventry Eagle job mounted upside down. Postwar C/E were gone but there was now a thriving local aviation industry looking for work. Pressing out Acme silencer halves was no different to pressing out lightweight aeroplane bits and pieces. Problem solved.