The above photo shows two of the most recognizable and important British machines of WW2 – the ubiquitous BSA WM20 parked in front of the revered Hawker Hurricane fighter. Some people think the Spitfire did all the damage during the battle of Britain but the wood and canvas Hurricane was the best of the two.
Hi all Bike-uriousers. The title is a bit tongue in cheek and I will explain later on why these two machines are so similar. But first, let’s travel back in time to 1936…
The British Empire reigns supreme – well, at least when it came to motorcycles. Yes Harley, Indian, BMW and a few other manufacturers were making good motorcycles, but Britain was the undisputed leader – in quality, quantity and diversity. There were literally dozens of manufacturers. At the time, the British Armed Forces needed a supply of motorcycles. Unlike the US, they did not have a small general purpose vehicle (the Jeep), and a lot of the logistics were carried out by dispatch riders on motorcycles. Now the Brits were in an envious position. They could select a single model or award contracts to several manufacturers, knowing that the leading Brit factories all made a very good product.
So, they set about finding the right machine. It had to be light, maneuverable, and able to traverse poor quality roads and dirt tracks. But above all, it had to be reliable. In those days, reliability was not near what we have now, and the army set an almost impossible specification that the successful bike had to be able to cover 10,000 miles with only regular servicing. This was back in the days when a rider would spend the whole weekend fiddling with their bike so it would get through the next working week.
This was just after the great depression. Having a steady government contract would be very handy for any manufacturer – a steady income, no after-sales service needs, a single customer. The deal could finance an assembly line and tooling which could then also be used to manufacture civilian bikes as well. All the major players submitted examples of their designs: Matchless, Norton, Ariel, Triumph Royal Enfield and BSA included. At the time BSA were the largest manufacturer and they had high hopes. Indeed, they pretty much designed a model dedicated to the contract – the BSA M20.
Pictured here is the dispatch area of the BSA factory. My personal WM20 has the C-number C4350974 so it was made in the same week or so that these machines were made. It’s actually possible that my machine is somewhere in the background!
The late 1930’s saw a fairly quick uptake of new technology – the overhead valve design. OHV engines produced much more power with less weight when compared with the earlier side-valve engines, and being able to cut weight on a motorcycle had many benefits. But the M20 was of a traditional side-valve configuration: a single cylinder 500cc lumbering brute that weighed well over 400 pounds dry with a modest 13 horses at the rear wheel. (re-fitting an M20 cylinder is a task for at least 2 people – those mothers are HEAVY!). They were going for simplicity and reliability over sheer performance, figuring these machines were destined to spend most of their time under 30mph.
The BSA failed the reliability test.
BSA went back to the drawing board, but stuck with the same design. After a make-up test in 1937, the machine passed – barely. The British Army now had a number of suppliers on their contract including Triumph (with a really cool OHV model), Norton with a similar 500CC side-valve and Matchless with a 350cc OHV model. Lucky for them, because World War 2 began shortly thereafter. Both the Triumph and the BSA factories were bombed during the Battle for Britain in late 1940. The Triumph factory was totally destroyed (all tooling, blueprints and molds were destroyed along with a great loss of life) but the BSA factory mostly survived intact. By now all manufacturing was focused on the war effort. BSA started churning out WM20’s as quickly as they could. Over the course of the war, they produced an astounding 126,000 machines. By comparison, the entire wartime production of Harley-Davidson was less than 100,000. Triumph was out of the picture as their factory had been destroyed, and the other manufacturers were much smaller than BSA – hence the WM20 became the mainstay British army motorcycle – used for just about everything imaginable. By now, it had become a solid and reliable bike with few vices.
The Triumph Coventry factory was completely destroyed in September 1940. Among the wreckage lays an unexploded bomb.
After the end of hostilities REME (the Royal Electrical and Mechanical Engineers) realized there were many advantages to having a single motorcycle model to maintain. It simplified tools, training and workshop space. They decided on the WM20 and this model continued to be the standard motorcycle for the army until the late 60’s, and for some allied countries like Australia, into the 70’s.
So how is the WM20 like a Sherman tank? Well, both models were somewhat inferior compared with the Axis machines. The Tiger and Panther tanks were clearly superior to the US equivalents. BMW and Zundapp motorcycles were also much better than the WM20. What separated these competing machines was production capacity. Shermans and WM20s were being manufactured at ratios close to 10:1 of the competing machines. If an allied tank or motorcycle was destroyed, ten more replacements arrived almost immediately.
So…why own one of these?
For me, as a Dutch ex-pat, the WM20 holds a special place in history and in my heart. My parents vividly remember the liberation of Holland in 1945, and these bikes were everywhere! So, as I ride my old “Wheezer” around town, I imagine the bike I am riding was actually there – somewhere. The old girl was dispatched from the factory in April 1941, so she is a true WW2 vet. For me, Wheezer is a poignant connection to my past.
Allied soldiers especially Canadians, were always welcomed in the traditional Dutch fashion during and after the liberation. Every year to this day, the Dutch people send 10,000 tulips to Canada as a thank-you to the Canadian liberators.
Canadian soldiers had a reputation for sitting on the tank rather than the seat. This allowed them to take 2 passengers rather than one. It seems there was never a shortage of volunteers! (the little girl on the far left of this image would have been the same age as my mother at the time). Photo from motorparade.blogspot.com
By now, even the casual reader on this site will have worked out that I like big singles! There is something simple and elegant about an engine with one piston. They are easy to maintain, repair and overhaul. The Thumpa sound is unique and soothing. The WM20 was the grandfather of all pre-unit BSA singles from 1937 onwards. First the ubiquitous B31 and B33 in various guises; and culminating in the venerable Goldstar.
They are rather lovely to ride as long as you stay under 50mph. They will go a bit faster (not much though). And, there is something reassuring about the steady, asthmatic Chuffa Chuffa Chuffa of an old side-valve single. The rigid frame, antiquated girder forks and smallish saddle make for a rather shaky ride – at least on poor roads. Maintenance is not difficult – the design is very simple and somewhat elegant. Electrics are standard Lucas stuff so if you have a basic knowledge of Brit bikes, you will be OK. You will need some special tools but these too are readily available. Replacement parts are available from Draganfly in the UK. They have a great parts fiche online and very knowledgeable staff. Parts prices are very reasonable and Draganfly shipping is inexpensive and quick. There is also an excellent website and active forum. Members are very happy to help out with any problem you can throw at them.
Here is my baby, named Wheezer. Not absolutely original though the paint is an exact color match to the original and the C- number on the tank is correct for the engine and frame number. I ride this to work most days.
Maintenance Tips
• Any WM20 you buy will have had a rich and colorful history which will include a fair share of less-than-careful owners. Quite likely there will be incorrect parts fitted, bodgy repairs and vital missing parts. Most of your work will focus on fixing these, but once fettled, there are not that many issues. (When I took delivery of my baby, a previous owner had somehow wedged the wrong transmission into the frame. To connect it to the engine, he “adapted” an old Norton primary case which precluded the presence of a LHS foot peg).
• The spacer between the carb and the cylinder will prevent the gas in the carb from boiling when hot. Note this is not a original carb, but a much later model.
• The two main design flaws are reasonably easy to sort. First, the engine produces quite a bit of heat. Once hot, the gas in the carburetor has a habit of boiling so hot that starts can be a problem. I inserted an aluminum spacer between the carb and the cylinder which has solved this issue. The second problem is the clutch. The clutch is of the dry type but it is housed in a wet primary case. If/when the clutch plates become fouled with oil, they will slip. Take care in sealing the clutch assembly and never over-fill the primary.
• Setting the timing can be a bitch, and the points will need regular adjustment (but see the Thorspark solution below).
• LED lighting is an inexpensive way to take the stress off an aging electrical system.
• Use 50 grade non-synthetic oil (40 grade in winter). Synthetic oils will leak out of the engine as fast as you can pour it in. Change the oil often.
• I changed out the lighting for modern LED units supplied by CDRC. These are direct replacements, brighter than original and decrease the load on the aging electrical system by around 90%.
• Remember, this is a 75 year old bike based on a design that is nearing 100 years of age. Some parts are going to fail. The most expensive of these is the magneto. These are usually very reliable but they will fail with age. Expect a good rebuild to cost upwards of $600. Being cheap… err… thrifty, when my mag failed, I replaced the points assembly with a Thorspark electro-mechanical pickup connected to a coil. For around $200, I bypassed the magneto and now have a reliable first-kick starter and never have to set or replace the points.
• The actual C-number this bike would have worn whilst engaged in combat. The great folks in the discussion forum can tell you the correct number for you frame. How cool is that!?
• The correct Smith’s chronometric speedo can be difficult to find. Specialist companies like Nisonger or Chronometrics in the UK will rebuild a non-functioning unit for $300-$400.
Buying Guide
• Expect to pay $5,000-6,000 for a reasonable running model, up to $10,000 for a 100 point concours example. When buying, take the bike for a longish ride, stop for a few minutes and try to start the bike hot. A poor, or non-starter could indicate a failing magneto (remember, that is gonna be expensive). Check that the speedo is working properly (again – a rebuild can be expensive).
• Don’t outlay too much when buying a “project”. Invariably, the magneto will be fried, you may need a new piston and rings, maybe a sleeve and a dynamo. Check the bike has the correct speedo. Its easy to think a couple thou is a good investment for such an old motorcycle. Remember, 126,000 were made so they are not rare.
• Do not expect these to be a great investment. They are not likely to increase in value more-so than other motorcycles. But do expect to enjoy riding. Most people form a strange, unexplainable bond with these old plodders. I sure have!
Parts Suppliers
Draganfly seems to have the best range of replacement parts (stuff to keep her running).
Stuart Bray specializes in used parts that are sometimes hard to find.
The WM20 website and forum is the best source of information and help with anything WM20 related.