The history of the AJS Stormer is intertwined with the Villiers Engineering Company as least as much as with the AJS motorcycle company of old.
Villiers was founded by Charles Marston in 1913. The original factory was on Villiers Street in Wolverhampton, but continued expansion required a move to a site of almost 18 acres on Marston Road in 1960. It was a remarkable factory for its time, able to produce almost every component needed to manufacture an engine. Raw materials came in one side of the factory, and complete engines were shipped out the other. The factory engineered and produced its own castings, forgings, electrical and ignition system components, and even its own carburetors. By 1960, Villiers had produced 2-1/2 million engines.
A bewildering variety of different models and variations comprised its product line over the years: 4-cycle industrial models for lawn mowers and small equipment (think Briggs and Stratton); more specialized units, such as the engine used in the venerable British Seagull outboard motor, and small engines for three-wheeled trucks and mini cars.
And, of course, they built single and twin-cylinder 2-stroke motorcycle engines. Villiers engines were used by practically all of the British motorcycle manufacturers who offered 2-cycle machines. (BSA was an exception with its Bantam, and AMC tried making its own 2-strokes briefly.) There were wide variations on these engines as well: Blower cooled versions, models with reverse gears, electric start, and other features so the engines could be tailored to military, scooter, and invalid carriage use.
Villiers motorcycle engines were rather low-output devices, built for economical, entry-level commuter motorcycles. They were often the butt of jokes; “gutless lumps,” they were sometimes called, or “lawnmower engines.” For most of the years it was in business, Villiers actively discouraged owners from trying to use their engines in a sporting capacity, and refused to provide hop-up parts or information, instead sternly warning that modifications along this line would void the engine’s warranty.
People raced them anyway. They were simple engines, easy to modify, cheap to repair, with spares both new and used easily available. Just what was needed in an era when two-stroke tuning was in its infancy, a black art really, and racers made their own performance parts. Though usually outclassed by the Continental engines of the period in works-level racing, many Villiers engines were raced successfully at sportsman events. The 122cc and 197cc models were very good for observed trials use, where high rpm and horsepower were not required. The DOT factory was notable in producing reasonably competitive scramblers from the 122/197 engines in the early 1950's. The very first 125cc Tourist Trophy (Isle of Man) road race was won by a Villiers-powered DOT, outlasting more powerful works entries from Mondial and Montesa.
THE VILLIERS 9E SERIES: THE TWO-STROKE GOES RACING IN EARNEST
The 197cc E series Villiers had been around since before World War II, with the Mark 3E model having the 59 X 72 mm bore/stroke dimensions and a hand type gear change. It was replaced by the 5E after the war, with little change except for a more-familiar foot gear change. It was superseded in 1948 by the 6E, which was of the same basic design as the 10D (125cc) engine with many common parts. These engines appeared in many British lightweight motorcycles of the era. Small detail changes to this model resulted in the 8E in 1953, along with a “competition version,” dubbed the 7E, with a high compression head and different gearing.
In 1955, Villiers introduced the updated 9E engine, with a more modern-looking, sleek appearance. It retained the bore / stroke dimensions of the earlier models, as well as the same humble design features, such as cast iron cylinder, t-bone crankshaft, and single row primary chain. A very unpretentious 8.4 horsepower was claimed. This very modest engine, however, was to be one of the pioneering two-strokes that would begin to seriously challenge the 4-strokes on the race tracks. The Villiers factory again stuck a toe in the racing waters, offering a competition version with higher compression, but little else.
It was left to the small British enthusiast manufacturers , such as Greeves and DOT, to experiment with ways of extracting more power. Alloy cylinder barrels and high compression heads were fitted, bumping horsepower up into the mid-teens to low 20's. Under such a power increase, the 9E's crankshaft usually surrendered in short order. Alpha Bearings Company began manufacturing a stronger, full-circle crankshaft to fix this problem. With the crank area strengthened, tuners got out their die grinders and went at the ports for even more power. At this point the crankcases themselves were flexing, clutches were slipping, and primary chain life was short. Alpha and Parkinson produced stouter crankcases, double-row primary chains were fitted and clutches were beefed up. The next weak link in the chain was the gearbox. The better scrambles riders at the time had to be sure to land off the jumps with the power off to avoid blowing the gearbox. Next came cylinder barrels with a full 250-cc of displacement, stressing the 9E’s design even further.
Even with all these deficiencies, a properly tuned 9E with a good rider aboard could often match 500cc machines of the era, as the Greeves and DOT works scrambles teams proved many times. The light weight and quick power of the two stroke was becoming a force to be reckoned with.
The popularity of the 250cc conversion kits for the 9E must have finally convinced Villiers that a full 250-cc engine was needed. In 1958 the A series engine was introduced. The first member of this new engine family, the 31A, was basically only a 9E with modified crankcases and a factory 250cc top end installed.
For all their shortcomings, the 9E and A series Villiers engines have to be one of the most raced, most modified engines in history. After the collapse of Villiers and the British motorcycle industry, the 9E ended up being manufactured as a kart racing engine by Invader, producing upwards of 40 bhp in its final versions. The 37A (trials version) was and is a decent trials engine. It is now being produced again by the reborn Greeves company in England. The 37A was also used in the AJS Trials motorcycle, which was offered briefly in 1968. Unfortunately, only a few of these machines were produced, and a very few survivors remain.
To their credit, Villiers finally realized: The two stroke racing revolution was for real. They needed a share of the growing scrambles market. Their traditional glacial pace of updating existing designs would not do. A new, designed from the ground up racing engine was required.
For Further Reading
Again, I have been intentionally brief with this history. There is a good knowledge base out there on Villiers engines, particularly the 9E, and I would rather be out in the workshop with my bikes than re-create the wheel here. For more information on Villiers engines, I suggest reading “Villiers Singles and Twins, by Roy Bacon, ISBN 0-85045-486-7. The book offers a history of Villiers, the motorcycle engines it produced, and brief write-ups on the various machines that used these engines. An impressively researched appendix of engine and machine specifications, including carburetor settings, is included, though Mr. Bacon admits he was unable to obtain specs on the vast number of engine variants produced.
Another superb book is “British Performance Two Strokes,” by Mick Walker and Rob Carrick, ISBN 1 85847 505 8. This book details the incredible variety of British racing 2-cycle engines that were around during the vintage era, many of which are virtually unknown in the USA. The creativity and resourcefulness of the British enthusiast manufacturers and race tuners shown in the book is, as the young folks say, “awesome.”
Both these books are unfortunately out of print and difficult to obtain in the USA. They often bring much competition and high prices on ebay. I got mine by googling the ISBN's, which led me to the great online secondhand book shops of Merry Olde England. They offered great service and reasonable prices. With email, paypal and credit cards, doing business across the Atlantic is easy, and Royal Mail will usually get your prize to you in about a week.
If you have a Villiers 9E under the bench that you would like to dust off and prep for racing, you need to read “Villiers Singles Improvement Handbook,” by Rob Carrick and John Wood. It is available for download at http://www.lortim.demon.co.uk/ . If you enjoy the two strokes of the vintage era, it’s an entertaining read, even if you don’t own a 9E.
