Identifying old Douglas motorcycles.

Part 1: 1907-26 Models 2-3/4hp, 3-1/2, and 4hp

Doug Cross, Doug Kephart, November 2004

Version 3.3
You will find the latest version and discussion of this document here - http://www.douglasmotorcycles.net/index.php/topic,488.0.html


To help you navigate, the full set of files in this series is as follows:

Part 1: Models 2-3/4hp, 3-1/2, and 4hp, 1907 to 1926
Latest version and discussion of this document here - http://www.douglasmotorcycles.net/index.php/topic,488.0.html

Part 2: Models of the 1920s and 1930s, excluding models in Part 1
Latest version and discussion of this document here - http://www.douglasmotorcycles.net/index.php/topic,489.0.html

Part 3: Postwar Models, excluding Vespa scooter
Latest version and discussion of this document here - http://www.douglasmotorcycles.net/index.php/topic,490.0.html


Codes and numbers of the main components.

In general during this period, location of the component codes and serial numbers are in the following locations: 

Frame: 2-3/4hp, left hand side of frame lug mounting countershaft/gearbox (when fitted!). Very early models sometimes in a circular pattern around right-hand rear frame lug. 3-1/2~4hp, right-hand saddle tube top. Sometimes unstamped on early machines but on later models this can indicate a dealer replacement.

Engine: 2-3/4hp, crankcase directly above rear cylinder. 3-1/2~4hp, crankcase top at rear edge alongside magneto.

Gearbox: 2-3/4hp, vertical joint face next to shift lever. 3-1/2~4hp, top at rear on projection for supporting clutch.


The first machine - the Fairy

Around 1905, Barter's Light Motors Ltd manufactured a 200cc side valve flat twin, clipped into a more or less standard bicycle frame, and known as the 'Fairy'. The crankcases were cast at the Douglas Brothers foundry in Bristol, 1905 to 1907. Only about three of these are known, so your chance of finding another one is, to say the least, remote!  It was not a Douglas but the immediate predecessor, and as such is not in the list below.

The early Douglas 350 cc side valve, 2-3/4hp - 1907 to 1926.

When Barter's Light Motors went into liquidation in 1907, Barter was invited to join Douglas, and a new and improved machine, the Model A, was exhibited in 1907. By 1910, the bicycle look had been supplanted by a more purposeful-looking motorcycle, the Model B, which nowadays is by far the most familiar old Douglas of the period.

The 2-3/4hp models tend to be the most difficult ones to date, because the model had a relatively long production run, and because at that time no-one seemed to have thought of putting code letters on the frames or engines. I have indicated approximately the range of frame and engine numbers for each year - these (like all the rest of the data in these tables) are taken from the Club Machine Register, and not from the factory records.

Since many people tried to keep their bikes running by 'mixing and matching' whatever could be made to fit and work, numbers tend to be a bit irregular in the real world, whereas at the factory at least the early frame and engine numbers would have matched. The gearbox numbers, on the other hand, would not have matched, at least at first, because they produced a large number of machines without any gearbox (or clutch) at all!

Some one must have noticed this discrepancy eventually, because by around 1915 they seem to have caught up. Around 1919, letter codes at the start of gearbox numbers were introduced - leaving the field open for more numerical mayhem in later years as people continued to swap boxes around as they thought fit. I've shown the commonest combinations as they are recorded in the Register. Some people even added gearboxes from other manufacturers - in these early days such hybrids were entirely genuine attempts to get something on the (pretty awful!) road that worked and was serviceable, so if it was put together around the right time, then it's a perfectly acceptable example of early motorcycle history. Don't knock someone's ancient runner just because it's not exactly like most of them that left the factory. Also the factory offered an aftermarket kit to convert single-speed models to two-speed. These came complete with chain, guard, longer drive belt to suit, and a gear change mechanism that could clamp on to the frame.

BUT!

But just to keep you on your toes, after ten years without a frame code, the factory seems to have introduced the CF frame prefix in about 1925 - never too late, I guess! However even this generalization may be misleading - a couple of years back Ronald van der Hoek in Holland told me that he bought what was described in an advert in a local paper as a "moped with frame for sale, 1920, for collector." - salvaged by a scrap yard worker. The 'moped' apparently turned out to be a 2-3/4hp Douglas! The frame has the code letters 'RR' stamped above the number, so maybe they did do some coding then, but so far no-one has let me know what it was. Any help with this would be appreciated - if I can update these lists it will help people like Ronald identify their finds.

For anyone with an unidentified wreck (or if you're lucky, something a bit better), the following numbers can be used as a guide - if you have roughly the right number for the year - give or take a year - then you've probably got at least contemporary bits. If one of your numbers or letter codes is way out, then you've probably got a hybrid. Don't worry - the main thing is to get the old thing going and enjoy it.

By all rights, Part One should end at 1920, where Part Two takes over. But for the sake of model continuity, the 2-3/4hp and the 4hp side valves are allowed to run over to the end of their production life without introducing new models developed from 1921 onwards. For these see Part Two, the 1920 and 1930s.

Model 2 3/4 HP (350cc) SV, 1907 to 1926

Year

Frame No., or letter

Engine No. or letter

Gearbox No. or letters

Any distinguishing features

1907-08

Within range of engine

100-159

Within range of engine

Diamond frame, stirrup front brake, belt rim rear brake, trembler coil ignition, atmospheric inlet, direct belt drive to rear wheel (single speed), pedal gear, reinforced bicycle front fork. Models A (1907) B (1908) of 340cc. Gland nuts on inlet manifold. Cylinder threads into crankcase.

1909

-

160-441

-

Model C. Magneto ignition, let into petrol tank, exposed external gear drive. Front suspension of bicycle blade forks on sprung links.

1910

-

442-1464

-

Model D. Proper light motorcycle sprung front forks, cradle frame, petrol tank not as deep. Tank sides faceted at front and rear where it narrows to meet the frame. Braced headstock. Two horizontal frame tubes below engine, one above the other. Lower rear fork joins saddle post at very bottom. Single bolt into port securing each end of inlet manifold (no gland nut.) Cylinders now mount to crankcase with two studs.

1911

-

1465-3999

-

Model D still direct belt drive, though two-speed gear below engine optional extra through factory or dealer installed. Light shield over external magneto gear drive. Petrol tank wider and sides curve gracefully inward at front and rear. Lower rear fork meets saddle post midway between two lower frame members. Model E, new frame with single frame tube below engine. Engine lower, no notch in petrol tank to clear magneto. Lower rear fork horizontal and joins saddle post slightly above engine rail. Chain to two-speed countershaft under rear cylinder, thence belt to rear wheel, no clutch or pedaling gear. Footboards fitted. Model F, 2-speed, clutch, hand start, open frame ladies model.

1912

-

4000-7100

-

Model G, chain to (single-speed) countershaft, foot pegs. Model H, 2-speed, with foot boards. Model J, 2-speed with foot pegs and option of drop handlebars. Model K, 2-speed with clutch and kick start. All with lower frame, single frame tube below engine which lines up with lower rear fork. Addition of a diagonal tube brace between saddle post and lower rear fork. Petrol tank and top frame tube slopes down at rear to accommodate lower saddle position. Countershaft unit moves rearward to base of saddle post, engine has mechanically operated inlet, fully encased internal magneto drive. Only Model G retains pedaling gear, now fitted to countershaft unit. Model L, specs as K, but ladies model with open frame.

1913

-

6940-125000

-

Models N, O, P, R respectively, ladies Model S. Return to curved inlet manifold with gland nuts, engine bore enlarged to 61mm for 349cc, stroke still 60mm. Unexplained overlap in numbers with prior year. Rear luggage carrier on back mudguard became standard. Model N (single-speed) last model offered with pedaling gear.

1914

-

12434-19000

-

Models T, U, V, W respectively, ladies Model X. Exhaust pipes enter silencer under engine tangentially, for a spiral flow effect. Switch to American Dixie magnetos when supplies of Bosh interrupted by hostilities. Last year single-speed offered.

1915

-

19500-29300

-

Model designations retained from 1914. Rear stand pivots at a brazed-on dedicated lug, rather than a hole through the rear fork tube. 3-speed gearbox available on some models. Model WD (War Department), large mud shield at front of frame, no clutch. Last year for Ladies model.

1916

-

27152-32428

-

Models U (foot boards) and V (foot pegs) both with either 2 or 3-speed. Model W, 3-speed and clutch. Model X still ladies model now with 3-speed and clutch. All models, new front fork, shackles are now inboard of girders, which has the leading tube straight and the trailing tube curved. Addition of Model WS, specs as W with swing arm rear fork, suspension by cantilevered leaf springs. Not believed to have gone into production. Wartime production for civilian use much reduced.

1917

-

32429-36178

-

Civilian production ceased February for duration of the war.

1918

-

36179-39257

-

Military models U,V,W with 2 or 3 speed gearboxes, optional clutch on 3-speed box. Many in khaki finish.

1919

-

39257-42958

G2(2-speed), G3(3-speed)

British-made EIC magneto. No diagonal tube bracing headstock to top frame member. (Surplus braced headstock frames used into early twenties.)

1920

-

42959-48200

G2(2-speed), G3(3-speed), G6(W20),G8(W20, 3-speed w/clutch)

Engine 60.8x60mm, 348cc. Models WD and W20. Stronger welded lug front forks, Ferrodo clutch lining. (Surplus 'veteran' forks used into early twenties to use up old stock.)

1921

-

48201-51800

LG(WD),CG(W21), HG, IG, KG,

Models WD and W21.

1922

-

51801-55370

-

2-speed. 3-speed with clutch.

1923

-

55371-64200

-

Model TS, 2-speed. Model W, 3-speed with clutch and kick start, Model 3SC, 3-speed all chain drive, fitted with small diameter inverted v-wedge brakes from OHV model (see Part Two.)  Cooling fins on inlet ports.

1924

-

64201-74500

LG(TS), NG(SW), OG(CW)

Model TS as before. Model SW, 2-speed with flywheel clutch. Model CW, 3-speed all chain drive with flywheel clutch, dummy belt rim brakes (about half rim diameter) front and rear.

1925

CF*****

74501-84200

LG(TS),OG(CW)

TS25, CW25 as before.

1926

-

84201-86791

LG(TS), A/OG(CW)

TS26 as before. CW26 with shock absorber in gearbox sprocket. Last year for venerable 2-3/4hp, And last year for belt drive, clutch-less, 2-speed with stirrup front brake (TS)!  Discontinued when stocks exhausted in favor of new 350cc Model EW, introduced late 1925 (see Part 2)

Note: where you see in the tables a code followed by three or more asterisks (e.g., CF/*****) the number of asterisks indicates the number of digits in the code number, a hyphen (-) indicates 'same as previous year' or 'ditto'.

The 3-1/2 and 4 HP side valve twins, 1914 to 23

Demand for larger bikes than the original 2-3/4hp ("two and three-quarter horsepower" - they still hadn't metricated then!) for sidecar use led to the introduction of new 500cc (3-1/2hp) and 600cc (4hp) models. These were all side valve machines, the early ones were used for wartime service. Civilian production continued until February 1917, when it ceased for the final year of the Great War.

3 1/2 and 4 HP (500/600cc) SV, 1914 to 1923

Year

Max Frame No. or letter

Max Engine No. or letter

Gearbox No. or letters

Any distinguishing features

1914

Within range of engine

?-1888

Within range of engine

Used for wartime service and for sidecar work - look for distinguishing paint (Khaki!) or for signs of having pulled a chair - clamp/bolt marks, or even a bent frame!  Cataloged as Model A and B (not to be confused with 2-3/4hp of 1907-08.)  Physically larger engine, 68 x 68mm, horizontally divided crankcase. Sitting on a large base the fore part recognizable as an oil sump. Consequently no oil compartment in the petrol tank. Chain to 2-speed countershaft unit behind engine with cone clutch, thence belt to rear wheel. Model A, foot rests, no clutch. Model B, foot boards, clutch and kick start. Bifurcated twin front down tube frame, these tubes have 'D' shaped cross-section (conventional round tubes on later models.)  Braced headstock. Rear brake block works on outside of belt rim (into V-groove.) 

1915

-

1897-2647

-

Larger 4hp model introduced, 74 x 68mm. Bosh magnetos unavailable due to war, Dixie followed by CAV substituted.

1916

-

2654-3794

-

3-1/2hp discontinued and A & B designations taken over by 4hp. Model A with 3-speed and clutch. Model B with same specs. Possibly there is a typo in the catalog and the A was still 2-speed. Archimedean screw oil pump replaced by rotary vane pump with auxiliary drip sight on petrol tank (all oil is still carried in the sump.)  Offered also with sidecar. All welded front fork blade of lighter design similar to 2-3/4hp of same year, replacing a welded-brazed lug fork used previously. Primarily EIC magnetos used from this point on. Rear brake block now operates on inside of belt rim.

1917

-

3803-4756

-

 

1918

-

5314-7210

G4/****(3-speed)

As a result of the utilization of engines for other purposes, stationary generators, etc. the numbering system is not very rational.

1919

-

7233-9988

-

Headstock no longer braced.

1920

-

9987-13050

G4/, G7/ (multi-plate)

Introduction of dry multi-plate clutch on gearbox. Model B20.

1921

-

13051-13600

G4/, G7/ (multi-plate), G11/

Model B21.

1922

-

13601-14280

-

Detachable cylinder heads with valve ports integral. Telescopic filler neck for oil sump. All lug brazed front fork. All chain drive version offered with sidecar outfit.

1923

-

14281-14713

-

Heated muff on intake manifold. Model B, solo, still belt drive. Model 4HC (sidecar), all chain drive. Model discontinued in favor of big OHV twins with sidecar the following year. 

Disclaimer

The information in these tables has been collected from various sources: factory records, registers of extant machines, Douglas publications, fellow enthusiasts, articles in the London Douglas Motor Cycle Club magazine the New ConRod, and personal knowledge. While every effort has been made to provide the most accurate information available, the information provide above is offered as a guide only. It is not recognized as official dating data by any licensing authority.

Doug Cross, Doug Kephart, and special thanks to Chris Wright and Malcom Meinertzhagen. November 2004