Hi all,

I have a couple of matchless competition scramblers, but find myself intrigued if not falling in love with, WM20's.
I participate regularly at rallies and would love a M20 to add to the trailer.

Just wondering what, if any of the girder fork models is the most popular and easiest to obtain spares for, considering, I believe there was a few engine changes in the early models.?

Cheers for any help. (though, I suspect, it'll be a case of which ever bike I can actually find for sale!)

Marty

email (option): marty.whyte@gmail.com

A 1939-45 WD M20 is by far the commonest and the most likely that you will find...Last year of girder fork production was 1947 but bear in mind no military M20s were built after the war....

Pre 38 models had a substantially different engine and there were also many other differences...They are nice bikes but much harder to find spares for...Ian

email (option): ian@wright52.plus.com

Thanks so much Ian. I've read you are quite the guru. Thanks for the information.
I certainly would love a 'war time' model, especially a girder fork model. I guess I'll be looking for a 40-45 model.

For reference only, (I'm not normally one to be sacrilegious and modify old bikes too much) assuming one can change the M20 conrod and barrel for a M21, are the piston and head the same ? Or did the M21 have different valves, head and piston?

Cheers.

Marty

email (option): marty.whyte@gmail.com

You would need an M21 flywheels and piston. Otherwise everything else is the same. Although an M21 carb bore is 1/16" bigger than an M20. I've done this conversion to my own M20 and it has more acceleration and more grunt on hills. I now also have a B33 piston waiting in the wings to take it out to 635cc.....Just for fun!! I'm still more than happy to stick to 50mph.

We were talking about this just a few days ago here:-

http://pub37.bravenet.com/forum/static/show.php?usernum=3155626639&frmid=16&msgid=1396241&cmd=show

Ron

email (option): ronpier@talk21.com

Thanks for the info. Very interesting.
That said, you say the carb bore is larger, but intake port in the barrel is the same?

email (option): marty.whyte@gmail.com

The several barrels that I've seen have all had 1 1/16" ports so I assumed they made 'One barrel fits all' But Ian says he's seen ports at both 1" and 1 1/16". But quite simple to remove the 1/32" from the port wall with a small grind stone or flap wheel.

The slightly bigger M21 carb has a smaller main jet than an M20 and I've known guys who just carry on with an M20 carb on their M21 engine. Ron

email (option): ronpier@talk21.com

Thanks very much Ron. Great information.

A quick question on engine and frame numbers.
As I suspect I won't be able to find a 'complete' WW2 bike in my budget, I may well have to start the search for a frame and engine. Were all the WM20 engine numbers stamped on drive side case under the barrel? I've seen some stamped numbers on a bolt lug at rear of engine??

And, are ALL ww2 period frames stamped WM?

Cheers.

Marty

email (option): marty.whyte@gmail.com

Some very early WD M20's (1939 models) are stamped KM20 but from 1940-45 they were all WM20 and as you say the engine number is by the breather on the N/S crank case. Crankcase halves were matched and often stamped with matching numbers on the front engine lug. Maybe sometimes a rear lug?

Ron

email (option): ronpier@talk21.com

If you are looking to buy an M20 but want to tune it so it will perform better why not simply buy a G3WO girder fork Matchless which are a 350cc OHV bike and much lighter and quicker than an M20.

As it happens I know where there are currently 2 G3WO projects for sale. One of them is very complete and in prima and just needs painting an assembling. Plenty of time to have it ready for Normandy next year. Email me off line if you are interested. Cheers John

email (option): Tinley@btinternet.com

['As it happens I know where there are currently 2 G3WO projects for sale.']...

Unfortunately two G3W0s won't make one M20..not enough metal...:laughing: .....Ian

email (option): ian@wright52.plus.com

Thanks Ron... Makes sense :)

Cheers John for the thought about the Matchy's for sale.
As much as I am a 'Matchy Man', (I have a 55 and 56 G80CS), I have been thinking about the M20 for its amazing history, and the fact that its' a grand old side valve.

I love the old Matchy's, but I'd like project with an engine that has some different character. As much as I love the old Iron head Matchy's, (I do miss my '49 G80S I sold to buy one of the Compy's) I feel the Beeza has some different character to provide me with.

As for the comments about 'tuning the M20 to perform better', I don't think I'll set out to do so, I was asking purely for future reference. I'd prefer to start with the M20 in stock trim to experience it in all it's SV glory. :)

Also, I'm in Australia, so unfortunately, getting bikes from the mother land is a bit cost prohibitive.
Cheers :)

email (option): marty.whyte@gmail.com

Hi Marty
Modak in Melbourne used to have good stocks of M20 parts, though I haven't had anything to do with them for some time. As for complete bikes, keep looking & best of luck.

Another sad day, they were a wonderful relic of days past.

Marty,

There is a '39 model listed on Just bikes, though why they call it a Gold Star is beyond me.

http://www.justauto.com.au/justbikes/motorcycles-for-sale/1939-BSA-500CC-24-GOLD-STAR-M-JBM4104236?backurl=http%3A%2F%2Fwww.justauto.com.au%2Fjustbikes%2Fsearch%3Fsearch_category%3DClassicBike%26current_page%3D5&backtext=Results

Cheers guys.
I'm definitely on the hunt. ;)

email (option): marty.whyte@gmail.com

Hello Marty.Where about in OZ are you.I will be putting back together 2 or 3 WM20's as rolling basket cases to put on Ebay in the next couple of month's.I am in west gippsland,vic. Or if you like self inflicted pain I am selling a 1000cc 1939 G14 V twin.Again a rolling basket case.I suppose it all depends on If you want to buy one fully restored or you restore one yourself.Regards,Sam.

email (option): smarwick@iprimus.com.au

Hi Sam, Have PM'd you. :)

email (option): marty.whyte@gmail.com