Hi all

What should the correct finish for a timing cover be on an 1940 m20 de luxe

I know a polished effect is not correct

Any advice on what it should be and how to Achieve it would be greatfully received

I have thought of
Bead blasting
Vapour blasting

I’ll hopefully be pointed in the right direction here

Best regards

Jo’b

email (option): jonnyob1@googlemail.com

John I've grit blasted lots of ally items (and stainless) with medium aluminium oxide grit which gives a very dry/matt finish. I then rub then over with wire wool to give a slight sheen. I can do this myself in no time in my own cabinet. I have got a tub of glass beads which will give a sheen finish after the grit, but it's an arse swaping the mediums.

But in my opinion, the best finish is Vapour blasting. But for me it means driving 5 miles to my vapour blasty bloke, wait 5-7 days, drive there again and part with dosh! Ron

email (option): ronpier@talk21.com

you going to do mine as well ??

email (option): chris dot astinbarker at btinternet dot com

AFAIK the early WDM20's had from factory silver painted crankcases and gearbox casings including the covers, similar finish as the carburettor.

Most of the times the paint has worn off but often can be found on the parts of the casings between the engine and gearbox plates.





Cheers, Michiel

Quite right michiel. The cases for the 39 and 40 'C' models were also silver lacquered. Ron

email (option): ronpier@talk21.com

Are you sure that it was not polished ?
Standard practice for most De-Luxe models was more polish & chrome plating than the std model.

email (option): bsansw1@tpg.com.au

Polished on a WD bike Trevor?

I don't know at what time BSA started to use silver lacquer on their engine and gearbox cases, but it fazed out during the early part of the war.

It was also used on Amal carbs back then.....Has anyone tried to get it off? Near impossible! Ron

email (option): ronpier@talk21.com

['Has anyone tried to get it off? Near impossible!...']

That's the problem...If the cases aren't finished with something equally durable and the bike is going to get used, the finish will soon fail and the whole thing will end up looking pretty poor cosmetically...

Better to refinish the cases and leave them in an 'as cast' finish than apply an inadequate finish I would have thought...Ian

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

Why would you want to try to get it off ??:relaxed:

Also the inside of the cases were silver painted which was a great help in cleaning them as the oil and dirt did not seem to adhere so much as usual.

This engine also had the cylinder silver painted:



Cheers, Michiel

John did say it was a M20 De-Luxe
John did not say it was a W M20.
BSA's model year started in August so there is a very good chance that John has a CIVILIAN M20 which either escaped being impressed or has been returned to it's pre service original finish.
Not sure exactly what date BSA stopped making civilian machines but I do have a 1941 catalogue ( Aug 40 - July 41 ).
It is the Overseas Edition as I presume by then civilian sales in the UK had been stopped.
The 39 catalogue lists the De-Luxe with chrome painted wheels against the std M20 that is just listed as having painted rims. Apart from that the finish appears identical , chrome tank with black pin lining & matt silver panels.
Remember that the entire range was silver in 39 to celebrate BSA winning some important silver wear

As for not being polished, all of the B & M series timing covers were polished.
Just have a good look at the surface finish on the inside and compare that to the outside.
They were just not polished to a mirror finish.
The catalogue is a pen & ink job so there is little to go on other than detailed descriptions in trade journals.
A photo would of course reveal the amount of polish by the type of reflection it had.

Did the War Office order any M20 De-Luxes ?

The catalogue is almost identical to the one on Leon's 30's page.
The print date is May 1940., well after the invasion of Poland in Sept 39
BSA's model year finished in July
Thus this is a 1941 overseas catalogue.
I also have a Feb 1940 copy ( not original ) of the home market catalogue ( has prices in £ )
This is the 2nd edition so it could be for the 40 or 41 season, but most likely the 40.

It is a bit hard to tell unless BSA actually put a model year in the catalogue, which season the catalogue covered.
Selling seasons overlapped model years
However pre-1950 a 1930 UK catalogue became the Australian 1931 catalogue so we wear a 1/2 model year behind the UK model season.
That changed in 50 & all model years became the same world wide.

email (option): bsansw1@tpg.com.au

Hi Trevor, yes there could be some confusion in the DeLuxe term as the KM and early WM ordered by the War Department had a few Deluxe features like the valanced rearmudguard and rubber mounted handlebar but were not Deluxe models like the civilian bikes as they not had the DeLuxe 'balloon' tank with a panel in the top but the standard balloon tank fitted with a winged filler cap and the usual panel in the 8 inch headlamp.

But think John was in this case referring to the early WD models.

"Why would you want to try to get it off ??"

You should know Michiel, I'm not one much for 'Patina' and whether it's for a repainted finish or raw alluminium, the old stuff needs to come off.:innocent: Ron

email (option): ronpier@talk21.com

john and i are both building WM20 de luxe, both supplied to the irish defence forces on a '39 contract, mine was issued in ireland in feb '40, johns a few weeks later...

email (option): chris dot astinbarker at btinternet dot com

Thanks everyone

Great information received as always

Paint on outer covers is in order so - crankcases & gear box shell is ok vapour blasted

Br

Job

email (option): jonnyob1@googlemail.com