classic motorcycle forum

Since the sprockets look to be in excellent condition, the chain may not be worn ?
Can you just pack the magneto up a bit higher on its platform ?
Or is the platform adjustable even, with slotted holes on one side ??

Isn't the internet brilliant?

Yes and no ?
Yes in your case.

I was searching for something electrically technical recently. And was 'amused' to see some words (which I had penned)
spat back at me and in complete denial of what I had wrote. Ain't AI wunnerful ??
Its like having a logical argument with a 2 year old, on steroids !

With no way to correct it ?

Are you guys ensuring that the clutch lifts perfectly evenly and squarely ?

If it worse when hot, then things have expanded a bit.
Backing off the springs a shade may be required ?

Are you snicking into neutral in the last bit of rolling to a stop.
And tried changing the gearbox oil....

My little Waratah 125 was bought from the original owner - decals still (mostly) visible.
He bought it from Williams Bros in Wentworth Ave in Sydney with his army demob pay.
And then rode it the 400 odd miles out to Hillston.
Think he said it took 2 days, but not sure on that.
At 30 mph, thats 13 hours !
Used all his petrol rationing coupons (4 ?) to do it.

Surviving bikes show differences in those toolboxes also, so its not just brochure creep ?

P.S. Tom Byrne in Wentworth Ave was the Excelsior Dealer then. 
About 100 yards up the hill from P & R Williams.
From advertising, the Excelsior was either 5 or 15 shillings dearer.
Byrnes did Triumphs also, and went on to become the main BMW Dealer.

Powerhouse Museums example
Their thick gold pinstripe is different to my thin gold twin pinstripes.
Maybe someone got it wrong ?
https://en.wikipedia.org/wiki/Waratah_motorcycles#/media/File:1948waratahmotorcycle.jpg

Are you clicking it into neutral in the last little bit while rolling to a stop.
And from 2nd, or 1st
Or attempting it once stopped.

Neutral (deliberately) has a lesser notch to it, to prevent the 1st to 2nd shift from hanging up.
It can be a very finicky adjustment of the clutch to get this action just right.

Whomever rebuilt it could have improved/changed/altered this ?
Changing the gearbox oil can sometimes work wonders with the action too.
Ain't old bikes fun !

No wonder the factory was getting back lotsa bikes with faulty running !
Sounds diabolical.

Just how do you "set the timing by moving the magneto gears"  ??
Or is that the time honoured method of tapping the gearwheel onto the taper, and then locking it with the nut ...

I was involved in the earlier posts !
Having a just postwar 125cc.
Bought from the original owner.
Identical to the Excelsior bar the black (vs maroon) and the decals.
And a few shillings in price.
The 2 shops were only a hundred yards apart in Wentworth Ave.

But don't recall exploring how this evolved pre WW2 ?
The Meritor wasn't mentioned ?

It is not entirely clear (to me) what method you are now going to use to set the ignition timing,
but I'd comment that if it is not going to verify that it is sparking at that 3/8" BTDC at full advance,
then we might be back to square one ?

And, the fuzzy logic of "hot gases" escapes me also. If BSA increased the tappet clearance, it is
very likely that they found the valve was growing with heat, until it lost any clearance.
At this point it may/would/could start losing compression - which may make them
a) difficult to restart
b) begin to burn a valve, since the hot gases would/could be continuously escaping.
And this would not be good.
Hopethishelps
Have fun !