Like Ian has just mentioned, he has no idea.
I have never seen a bike that will take so much abuse and still go forward
Got a nice photo of a barrel some where that the pin clip had fallen out & the pin had worn a groove right through the linner
The piston sat at about 5 deg off horizontal and had a gap of about 1/8" on the worn side of the bore.
And yes it ran, blew a lot of smoke over 1/2 throttle but it ran.
If you pop over http://www.bsanational.org.au/bsa2006/Saturday_Photos.html in the photos is another WM20, found in a chook shed , not touched for at least 40 years.
The finder put some fuel in it, gave the carb a shot of starting fluid & rode it home .
The next week he rode it to the rally.
He did about 10 laps of Mt Pannorama flat chat ( note the deflection in the rear tyre ) then finished the 100 mile run.
Ian I live in a little seaside town called Brick New Jersey USA.
This weekend we are having a First Infantry Division meeting at my son’s farm
So far we have two Matchless, two Indians two Harley WLA, my KM20 and a couple of Chinese/USSR bikes made over to look like BMW.
We so far have 3 Weapons Carriers, assorted Jeeps, halftrack, with probably another 20 vehicles on the was.
The group have a strong preference for Norton, Matchless or Indian. One guy warned me he has never seen an M20 that ran. “Don’t waste your money”
After we hauled off the trailer, I kicked her over three time at full throttle full choke full decompression. Found TDC Decompress a little thin full advance and a good kick.
Started first kick. That got their attention.