AJS V4
Encyclopedia
The AJS V4 started out as a prototype air-cooled V4 road bike, but became a water-cooled and supercharged racing bike.
at the time that there would be the option of replacing the forward mounted chain driven dynamo with a supercharger
. The AJS used a rigid frame with girder forks.
for testing, wearing a Zoller supercharger, driven at half engine speed, and fed by a single Amal
TT carburettor. (The ERA
GP cars of the time used a larger Zoller supercharger.) It made 51.5 bhp at 6000 rpm. All exhaust ports now faced forward, and a branched inlet manifold fed the engine with 8 psi of boost. The engine was now mounted in the same frame as the 500 cc OHC single TT racers, and used a four-speed Burman
gearbox with a dry clutch.
In 1936 Harold Daniell
and George Rowley rode the AJS supercharged V4s in the Isle of Man Senior TT
, but despite its high top speed, it lacked acceleration. Both riders retired due to mechanical problems.
designer, to do a complete redesign.
The result was a water-cooled version with barrels and cylinder heads cast in pairs, and fitted with enclosed valves. All exhaust ports now faced rearwards. Initially a thermo siphon
design with a radiator on each side of the front frame downtubes, an impeller type water pump was soon added to the left side of the crankshaft to further aid cooling. Supercharger
boost was reduced to 6 psi. Instead of the previous pressure lubrication, oil was now added to the fuel. The new duplex frame had integral rear plunger suspension housings, and the Webb-type girder forks were now graced with a deep finned alloy 8 inches (203.2 mm) TLS front brake. The bike used a 21 inches (533.4 mm) front tyre, and a 19 inches (482.6 mm) rear. It had a six imperial gallon fuel tank.
In May 1939 A R (Bob) Foster entered one in the North West 200
, but it flooded on the start line.
At the 1939 Isle of Man TT two bikes, ridden by Walter Rusk and A R (Bob) Foster, were 11th and 13th, and the supercharged BMWs of Georg Meir and Jock M West took the first two places. Though capable of high speeds, the AJS V4s did not handle well, and blew head gaskets in practice.
At the 1939 Ulster GP
, the last GP before the War, the two bikes led from the start against Nortons
and a supercharged four-cylinder Gilera
, but halfway round the first of the 14 miles (22.5 km) laps, already timed at 135 mi/h on one section, A R (Bob) Foster retired with plug trouble. Rusk completed the first lap at a record breaking average of 100.03 mi/h and a lead of 34 seconds. On the third lap a fork link broke forcing retirement. It is believed that this was caused by mistaken fitment of a 7R fork link instead of the stronger V4 part during servicing.
In 1939 the 405 lb (183.7 kg). dry sump V4 was the first bike to lap the Ulster Grand Prix course at over 100 mi/h. Then World War II intervened.
In June 1946, the AJS V4 finally won, at Chimay
in Belgium
, ridden by the same Jock M West who had defeated the AJS on a BMW
in the TT before the War, and was now AJS Sales Manager. Walter Rusk did not survive the War, and Jock's mount was the bike Rusk had ridden. A week later at Albi, France, Jock West was in the lead when a crankpin seized and locked. (When Sammy Miller
acquired the engine from Jock West thirty years later to rebuild the AJS V4 for his museum, he found the crankpin still seized.)
AJS was already developing another supercharged engine, the AJS Porcupine
, but, three months after the Albi race, the FIM
banned all forms of forced induction for motorcycle racing.
The engine used by Walter Rusk in the Ulster GP, with 7.9:1 compression and 16.5 lbf/in² (114 kPa) of boost, made 55 bhp at 7200 rpm on a dynamometer.
The 1935 Olympia Show bike
In 1935, at the Olympia Show, the Bert Collier designed air-cooled sohc AJS 50° V4 was first displayed. It was a fully equipped road going version, which did not make it into production. This first version used a common crankcase with four individual cast iron cylinders and separate alloy heads, with exposed hairpin valve springs, and a 180° crankshaft with forked conrods. There was a central carburettor for each pair of cylinders, and fore and aft exhausts. The single overhead camshafts were chain driven. It had chain primary drive in an oil bath primary chain-case, and a wet clutch. It was stated by AJSAJS
AJS was the name used for cars and motorcycles made by the Wolverhampton, England, company A. J. Stevens & Co. Ltd, from 1909 to 1931, by then holding 117 motorcycle world records, and after the firm was sold the name continued to be used by Matchless, Associated Motorcycles and Norton-Villiers on...
at the time that there would be the option of replacing the forward mounted chain driven dynamo with a supercharger
Supercharger
A supercharger is an air compressor used for forced induction of an internal combustion engine.The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally aspirated engine, which allows more fuel to be burned and more work to be done per cycle,...
. The AJS used a rigid frame with girder forks.
The 1936 racer
In the spring of 1936 a new racing version with alloy barrels appeared at BrooklandsBrooklands
Brooklands was a motor racing circuit and aerodrome built near Weybridge in Surrey, England. It opened in 1907, and was the world's first purpose-built motorsport venue, as well as one of Britain's first airfields...
for testing, wearing a Zoller supercharger, driven at half engine speed, and fed by a single Amal
Amal (motorcycle)
AMAL is a British carburettor trademark. AMAL were the suppliers of carburettors to the British motorcycle industry and their products were present on the products of the largest British motorcycle manufacturers such as BSA and AMC...
TT carburettor. (The ERA
English Racing Automobiles
English Racing Automobiles was a British racing car manufacturer active from 1933 to 1954. Currently the ERA trademark is owned by a British kit-car manufacturer.-Prewar history:...
GP cars of the time used a larger Zoller supercharger.) It made 51.5 bhp at 6000 rpm. All exhaust ports now faced forward, and a branched inlet manifold fed the engine with 8 psi of boost. The engine was now mounted in the same frame as the 500 cc OHC single TT racers, and used a four-speed Burman
Burman and Sons Ltd
Burman and Sons Ltd, of Ryland Road, Birmingham, England, manufactured Burman-Douglas steering gear.Their recirculating worm and ball design of steering gear was fitted to pre-war vehicles such as the Ford Eight and the Ford Prefect, the Bedford CA, plus many other vehicles - both pre and post-war....
gearbox with a dry clutch.
In 1936 Harold Daniell
Harold Daniell
Harold Daniell was a British professional Grand Prix motorcycle road racer who competed in the 1940s and 1950s...
and George Rowley rode the AJS supercharged V4s in the Isle of Man Senior TT
1936 Isle of Man TT
The 1936 Isle of Man Tourist Trophy saw Norton rider Jimmie Guthrie win the Senior, and come fifth in the Junior. The Junior was won by Freddie Frith in his first year on the Norton team, and the Lightweight was won by Bob Foster on a New Imperial....
, but despite its high top speed, it lacked acceleration. Both riders retired due to mechanical problems.
The 1938 racer
Considerable work must have been done at the new AMC race shop, because the next version did not appear until 1938, and when it did it had a plunger rear suspension, better brakes, revised and lighter induction manifold, and raised compression. The engine had been mounted further back in the frame to improve rear cylinder cooling. A R (Bob) Foster rode one in the 1938 Senior Isle of Man TT, but it retired, from overheating, after only two laps.The water-cooled 1939 AJS V4 racer
Where other companies might have cut their losses at this point, AMC did not. They commissioned Matt Wright, former New ImperialNew Imperial Motors Ltd
New Imperial was a British motorcycle manufacturer founded by Norman Downes in Birmingham, between 1887 and 1901, and became New Imperial Motors Ltd in 1912, when serious production commenced. New Imperial made innovative motorcycles that employed unit construction and sprung heel frames long...
designer, to do a complete redesign.
The result was a water-cooled version with barrels and cylinder heads cast in pairs, and fitted with enclosed valves. All exhaust ports now faced rearwards. Initially a thermo siphon
Thermosiphon
Thermosiphon refers to a method of passive heat exchange based on natural convection which circulates liquid without the necessity of a mechanical pump...
design with a radiator on each side of the front frame downtubes, an impeller type water pump was soon added to the left side of the crankshaft to further aid cooling. Supercharger
Supercharger
A supercharger is an air compressor used for forced induction of an internal combustion engine.The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally aspirated engine, which allows more fuel to be burned and more work to be done per cycle,...
boost was reduced to 6 psi. Instead of the previous pressure lubrication, oil was now added to the fuel. The new duplex frame had integral rear plunger suspension housings, and the Webb-type girder forks were now graced with a deep finned alloy 8 inches (203.2 mm) TLS front brake. The bike used a 21 inches (533.4 mm) front tyre, and a 19 inches (482.6 mm) rear. It had a six imperial gallon fuel tank.
In May 1939 A R (Bob) Foster entered one in the North West 200
North West 200
The North West 200 is a motorcycle race meeting held each May in Northern Ireland. The course, made up of public roads running between the towns of Portstewart, Coleraine and Portrush is one of the fastest in the world, with speeds in excess of . It is one of around fifteen events run on public...
, but it flooded on the start line.
At the 1939 Isle of Man TT two bikes, ridden by Walter Rusk and A R (Bob) Foster, were 11th and 13th, and the supercharged BMWs of Georg Meir and Jock M West took the first two places. Though capable of high speeds, the AJS V4s did not handle well, and blew head gaskets in practice.
At the 1939 Ulster GP
Ulster Grand Prix
The Ulster Grand Prix is a motorcycle road race that takes place on the Dundrod Circuit near Belfast, Northern Ireland. The first races took place in 1922 and in 1935 and 1948 the Fédération Internationale de Motocyclisme gave it the title Grand Prix d'Europe...
, the last GP before the War, the two bikes led from the start against Nortons
Norton (motorcycle)
Norton is a British motorcycle marque, originally from Birmingham, founded in 1898 as a manufacturer of "fittings and parts for the two-wheel trade". By 1902, they had begun manufacturing motorcycles with bought-in engines. In 1908, a Norton-built engine was added to the range...
and a supercharged four-cylinder Gilera
Gilera
Gilera is an Italian motorcycle manufacturer founded in Arcore in 1909 by Giuseppe Gilera. In 1969 the company was purchased by Piaggio, which now holds six marques and is the world's fourth largest motorcycle manufacturer.-History:...
, but halfway round the first of the 14 miles (22.5 km) laps, already timed at 135 mi/h on one section, A R (Bob) Foster retired with plug trouble. Rusk completed the first lap at a record breaking average of 100.03 mi/h and a lead of 34 seconds. On the third lap a fork link broke forcing retirement. It is believed that this was caused by mistaken fitment of a 7R fork link instead of the stronger V4 part during servicing.
In 1939 the 405 lb (183.7 kg). dry sump V4 was the first bike to lap the Ulster Grand Prix course at over 100 mi/h. Then World War II intervened.
In June 1946, the AJS V4 finally won, at Chimay
Chimay
Chimay a Walloon municipality located in the Belgian province of Hainaut. On January 1, 2006, Chimay had a total population of 9,774. The total area is 197.10 km² which gives a population density of 50 inhabitants per km²...
in Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...
, ridden by the same Jock M West who had defeated the AJS on a BMW
BMW motorcycles
BMW's motorcycle history began in 1921 when the company commenced manufacturing engines for other companies. Motorcycle manufacturing now operates under the BMW Motorrad brand...
in the TT before the War, and was now AJS Sales Manager. Walter Rusk did not survive the War, and Jock's mount was the bike Rusk had ridden. A week later at Albi, France, Jock West was in the lead when a crankpin seized and locked. (When Sammy Miller
Sammy Miller
Samuel Hamilton "Sammy" Miller, MBE is a championship winning motorcycle racer, in both road racing and trials. He was awarded an MBE in the 2009 New Year Honours.-Career:...
acquired the engine from Jock West thirty years later to rebuild the AJS V4 for his museum, he found the crankpin still seized.)
AJS was already developing another supercharged engine, the AJS Porcupine
AJS Porcupine
-Racing history:The motorcycle was originally designed by AJS to be supercharged, as were a number of pre-war racing bikes, but the FICM banned supercharging in 1946. The motor was then worked on to allow it to perform without a supercharger...
, but, three months after the Albi race, the FIM
Fédération Internationale de Motocyclisme
The Fédération Internationale de Motocyclisme is the governing body of motorcycle racing. It represents 103 national motorcycle federations that are divided into six regional continental unions....
banned all forms of forced induction for motorcycle racing.
The engine used by Walter Rusk in the Ulster GP, with 7.9:1 compression and 16.5 lbf/in² (114 kPa) of boost, made 55 bhp at 7200 rpm on a dynamometer.