classic motorcycle forum

I don't know how to differentiate them! So far as I know even the frame numbers were similar, but I only have a handful to study. Best to have provenance of a bike with Waratah on the tank, known original owner, original registration or whatever.

It wouldn't surprise me if there was a little bit of "old stock" syndrome, with slightly out of date bikes or older, lower cost parts fitted to the bikes to be sent out. But it was all about commercial pragmatism: Williams Bros were a big (huge, in the automobile trade) and well-established firm, importing and selling quite a number of Waratahs, so clearly they wouldn't be accepting or selling old junk.

My working hypothesis is that Waratahs were built in the UK by Excelsior (from 1930-on) and shipped to Williams Bros in Sydney.
 
Leon

Thanks for that. I do have a couple of Mk XVI-A engine numbers (prefix AXF) from Waratahs so that will work.

I'm a bit confused because the Villiers book (Browning) says the Mk XVI-A has an "aluminium deflector piston" while Waratah guff in late 1935, for its 1936 model, says two exhaust ports (tick), 67x70 (tick), detachable alloy head (tick), full roller big end (tick), extra long gas tight bronze main bearings (tick), but "alloy flat top piston"!

The XVII-A (BYX prefix) had the flat top piston, but ball mains!

Not to worry - it's a 250 (notice I didn't say 247 or 249!!) Villiers. Should be enough.

Yes, R, all Waratahs from Excelsior from about 1930, prior to that from Sun Cycle & Fittings. Even Excelsior frame numbers, but not necessarily exact Excelsior models.

Cheers

Leon

Hi Billington,

In your photo the rubbing block is well past the opening ramp: when it is in this position the points gap should be about 0.012".

For most of the rotation of the magneto the points should be open about 12 thou; for the rest the points should be closed. Only when the rubbing block hits the ramps and begins opening the points will the gap pass (instantaneously) through 0.003". (And again when closing, but this plays no role in the spark.)

When BSA talks about the points being open 0.003", they mean that the rubbing block has hit the ramp and the points have opened about a quarter the way to fully open (0.012"). This defines an exact point in the rotation of the magneto.

You've asked for help, we've provided it with care an attention. Have you considered accepting it? Humour us. Try it out.

Cheers

Leon

That is interesting.

In particular the 0.004/0.004" valve clearances in 1931 seem very optimistic, very precise. I must admit that I don't use a feeler gauge at all on my vintage bikes, but just give them a jiggle to make sure they're ok. I reckon 4 thou on an exhaust valve wouldn't pass my jiggle test!

As for setting ignition timing using engine at TDC and mag on full retard, I do it all the time - it's my standard method on the side of the road. Easy to find TDC, easy to spot the points starting to open (in the BSA case open 3 thou - a quarter of the way to 12 thou). Done. Works every time. But, depending what has been done to the mag over the years, it sometimes means too much advance is available to the engine with the lever at full advance, so maybe the bike runs best on no-quite-full advance. Over-advanced ignition is bad. Not a problem for an experienced rider, but bad in the hands of a novice. Best to set the timing at full advance if you're at home in the shed.

Seriously, I wish Billington all the best with his bike, but he seems to misunderstand the BSA instructions yet stands by his misunderstanding even when others try to explain. I have done my best.

Cheers,

Leon

Hopefully you have set the points gap to 12 thou and set the magneto timing correctly. https://classicmotorcycleforum.com/index.php?topic=6299.msg31348#msg31348

If you haven't, do it now.

Leon

Ditto. Also time to check the main shafts for wear and roundness - the wear is some distance in from the end so if the shafts are not parallel and round your new bushes will be wasted.

Also the bushes need to be in line when you're all done. I usually make them a thou (0.001") under size, then ease them out with an adjustable reamer fitted with a pilot. The pilot fits into the bush in the opposite side of the crank case to keep the reamer parallel while its cutting. Not a difficult job, but you need the right tool. (I borrow my adjustable reamers from a friend who has a boxed selection - last forever if only used on phospor bronze.)

Leon

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