Hi all
Someone recently asked me about a difference in oil tank filler neck & the angle it sits at
He felt there may have been different types over the years
I admit I forgot about it until today when putting my m20 back together for a trip next week - I also noted that my 44/45 bike has a chamfered edge drain bolt at the bottom of the tank - where as a project sat on my bench has a std bolt & fibre washer

Has anyone got any information on differences in oil tanks
Filler neck angle change
Oil brain bolt change -
Br
Job

email (option): jonnyob1@googlemail.com

I'm not aware of a different shaped WM20 oil tank John? I can't recall seeing the tapered drain plug. The gearbox drain plug is the tapered type. Maybe they modified the plug later?

Ron

email (option): ronpier@talk21.com

Yes the oil tank drain bolt & the gearbox drain bolt are both the same

It’s most odd

Jo’b

email (option): jonnyob1@googlemail.com

I've noticed small variations in the oil tank filler necks over the years (height and angle)...Unfortunately I didn't note which years or models though as it wasn't a matter of concern at the time and didn't affect anything else...Ian

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

Most likely a B series tank fitted into an M series frame

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

I'm assuming you mean pre war B Sreies...?..The post war B Series tank is completely different and they all have a screw in cap....

I've never seen a tapered oil tank drain plug...From memory, the gearbox drain plug and the oil tank drain plug have a different thread don't they..??..I'd have to check that one to be certain...Ian

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

Is this the taper we are talking about?

Rob

email (option): robmiller11(a)yahoo.co.uk

Hi rob
I will take photos later & send to you - perhaps you can post for me
Br
Job

email (option): jonnyob1@googlemail.com

Will do John.

Rob

email (option): robmiller11(a)yahoo.co.uk

Johns pictures, this is attempt 3 at posting them as I keep pressing the wrong button and deleting it.

John either you need to chuck that stupid smart phone away or I need to stop drinking whisky.

email (option): robmiller11(a)yahoo.co.uk

Thanks Rob

email (option): jonnyob1@googlemail.com

I've been looking in the spares lists for an answer and its a little puzzling.

The 1939 and 1940 civilian spare parts list have different part numbers for the M20 oil tanks and caps, did the size of the pre war screw filler cap change at that time? any way that's irrelevant the important number is drain plug EA95 which is also shown as the part number of the 1939 G14 crank case drain plug.

The military contract spares lists show the following part numbers.

Contract - Oil Tank - Drain plug
C6126 - 66-8350 - 31-8383
C6654 - 66-8350 - 31-8383
C7287 - 66-8350 - 31-8383 - WM20 25001-42000
RAF ect? - ? - ? - WM20 42001-44212
C9310 - 65-8442 - EA95 - WM20 44213-53212
C10655 - 65-8350 - EA95 - WM20 53213-53412
C11101 - ? - ? - WM20 53413-61412
C12586 - ? - ? - WM20 61413-61447?
C11101 - ? - ? - WM20 61448-63447
C12424 - 65-8350 - EA95 - WM20 63448-71447
? - ? - ? - WM20 71448
S13873 - 65-8350 - EA95 - WM20 71449-71483
C13909? - ? - ? - WM20 71484-71508
C14052 - 65-8350 - EA95 - WM20 71509-71817
C13290 - 65-8442 - EA95 - WM20 71818-81817
S1048 - 65-8442 - EA95
S2603 - 65-8442 - EA95
S5209 - 65-8442 - EA95
S7218 - 65-8442 - EA95

They all show the crank case drain plug and gearbox drain plug as part numbers 28-243 and 28-43

So in conclusion from WM20 18001 on there are two different oil tanks used on military machines 66-8350 and 65-8442, but the difference doesn't appear to be the drain plug of which there are also two 31-8383 and EA95 because EA95 is sometimes used with both oil tanks.

Clear as mud.

Rob

email (option): robmiller11(a)yahoo.co.uk

Didn't we establish through Nathan that the filler caps altered in 1939/40? Ron

email (option): ronpier@talk21.com

That was the steel or brass butterfly, both would fit either military oil tank even if they are different?

Rob

email (option): robmiller11(a)yahoo.co.uk

Hello
The drain plug on Johns oil tank is 28-43
My earliest record of the part number is B models of 1930
Ie B30/3 and 4
It is a crankcase drain plug at this point in time.
John check to see if it has the plied arms mark.
It is also used of Y13 and G14

It the same thread as EA95, of which I have at least 5 different examples as it was used from the early 20’s.

BSA regularly used some nuts and bolts on nearly all model’s, that originated in the teens.

For instance the gearbox inspection cover bolts and filler cap, were first used on Round tanks.

Many nuts and bolts on a WM20 are from the 20’s
And early thirties.
Some of the models include flat tank,Sloper v twin, blue star Etc

Front axle on a WM20 was first used in 32, the same year as the combo levers were patented.

Hi Darren

Could you supply some pictures or dimensions of your 5 different EA95s and is it possible that one of them is 31-8383?

Rob

email (option): robmiller11(a)yahoo.co.uk

Thanks folks for all

Now that I know mine is for now a bit of an oddity - I will carry one of these in a bag as if I lose it I am potentiality in a spot of bother

Br
Job

email (option): jonnyob1@googlemail.com

I just stumbled on this today. Are we concluding 28-0043 is the taper seat and 28-0243 is the flat seat using a fibre washer 2-4553? Both have the same thread and can be found as gearbox and oil tank drain bolts?

Strangely one of my gearbox taper seat drain bolts was packed with grease and had a ball bearing in it?

email (option): pes.sales@btconnect.com

I'm still looking for a NOS oil tank if anyone has, or comes across one....Ian

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

Thanks to Steves KM20 chart and another look through the spares lists I finally understand the difference between the two drain plugs used on early and late military M20s, this is 31-8383 which was also used pre war on the G14.

Rob

email (option): robmiller11@yahoo.co.uk