DME Circulars

During 1940 a system was introduced to control/request/demand modifications to existing equipment in use (not limited to motorcycles).
Some of these modifications were lateron standardised by the motorcycle manufacturers.
The instructions were devised by "The Directorate of Mechanical Engineering" and changes/guidelines were published in so called D.M.E. (modification) circulars.
The existence of those circulars is known for quite a number of years (2008) based on a listing found in "Questionaire on the Norton, B.S.A. Matchless Ariel and Royal Enfield motorcycles" prepared by the Royal Artillery Mechanical Traction School (R.A.M.T.S. 14/4 October 1943) showing the titles of circulars pertaining to motorcycles.

Unfortunately only very few of the individual circulars have surfaced over the past decade. Story goes that they were destroyed after a certain time to prevent the accumulation of too much paperwork.

Some of the descriptions are fairly cryptic giving hardly enough information to understand what is meant to be done.
Some others lift the vail on when certain changes came into being, e.g. the provision for immobilizing or the introduction of pannier equipment.

Anyone with access to DME circulars is requested to come forward for the greater understanding.

Below is a survey of the original D.M.E. cirulars (transcripted for clarity) valid for Nortons.

Particulars of D.M.E., Circulars
affecting Norton, B.S.A. Matchless, Ariel and Royal Enfield Motor-
cycles, available up to October, 1943.
Circular No.	Date	Purport	Motorcycle

		IMMEDIATE ACTION
B.40	28-10-1940	Fitting of Security Bolts to prevent damage to valves	Norton
B.141	12-5-1941	Fitting of new headlamp mask and removal of dipper switch.	All M/C’s
B.125	21-7-1941	Provision for immobilizing.	All M/C’s
B.155	6-3-1942	Fitting pannier bags and pillion seat conversion sets.	Norton
B.173	8-4-1942	Carburetter – adjustment for petrol economy.	B.S.A. Norton
B.301	21-5-1942	Spanner for dynamo securing strap nut.	All M/C’s
B.417	31-3-1943	Dynamo bracket screw at driving pinion end of Lucas Magdyno.	Norton, B.S.A., Ariel, R.Enfield

		WHEN NECESSARY
B.19	1-10-1940	Petrol tank lugs. (Fracturing).	Norton
B.46	19-11-1940	Rear stand and mudguard.	Norton
B.41	24-2-1941	Fitting flexible petrol and oil pipes.	Norton
B.212	16-11-1941	Modification to horn bracket.	Norton
B.173	8-4-1942	Carburetter – adjustment for petrol economy.	B.S.A. Norton
B.257	12-5-1942	Fitting panel air cleaner in Mid. East.	Norton
B.210	15-5-1942	Rear stand method of repair.	Norton
B.212/1	16--7-42	Amendment No.1. Cancels B.212	Norton
B.323	31-7-1942	Dynamo and regulator wiring.	All M/C’s
B.304	7-9-1942	Change speed mechanism - Bushes fitted to cam plate and spring cover plate.	Norton
B.413	17-2-1943	Petrol pipes.	Norton

Circular No.	Date	Purport	Motorcycle

		GENERAL INSTRUCTIONS
B.106	26-4-1941	Dublchek Schrader valve caps.	All M/C’s
B.174	8-8-1941	Ignition timing.	All M/C’s
B.211	14-10-1941	Procedure for reporting faults on A.F.G.889.	All M/C’s
B.217	31-10-1941	Maintenance of Spark Plugs	All M/C’s
B.260	31-10-1941	Kickstarter ratchet gears.	All M/C’s
B.407	4-2-1942	“Target” fuel consumption figures, (M.P.G.)	All M/C’s
B.200	20-3-1942	Tyre Pressure.	All M/C’s
B.127	16-5-1942	Method of fitting chevron tyres.	All M/C’s
B.268	12-6-1942	Replacement of Tecalemit grease nipples.	All M/C’s
B.313	8-7-1942	Initial Inspection.	All M/C’s
B.325	8-8-1942	Limit of wear outer covers.	All M/C’s
B.402	21-11-1942	Handlebar grips – rubber substitute, method of fixing to handlebars, and twist grip rotors.	All M/C’s
B.400	21-1-1943	List of tyre pressures. (Cancels B.200).	All M/C’s
B.456	25-2-1943	New range of lubricants W.D. “B” Vehicles.	All M/C’s
B.345	11-5-1943	Security bolt (front wheel).	All M/C’s
B.400/1	12-5-1943	Amendment to B.400.	All M/C’s
B.517	16-7-1943	Defects, rendition of A.F.G.889 in accordance with A.C.I.2240 of 1942 (Cancels B.211) .	All M/C’s