Royal Enfield Bullet
Pre-war Royal Enfield Bullets
The 1948 G2 Bullet and Tony Wilson-Jones
Trials and competition Bullets
The 350cc Royal Enfield Bullet engine
The Enfield Albion gearbox
The 500cc JS Bullet and the casquette
Full width brake hubs & cylinder head work
Magneto ignitions and alternator electrics
Coil ignition, 17-inch wheels, 6-inch brakes
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Neville & Mark Cross
1954 Royal Enfield Bullet Specifications
Type: Air-cooled OHV single
Capacity: 346cc (350cc)
Bore & Stroke: 70mm x 90mm
BHP: 18 @ 5750rpm
Compression ratio: 6.2:1
Transmission: 4-speed, multi-plate wet clutch
Brakes: 6-inch drums front and rear
Electrics: 6-volt, magdyno
Front suspension: Telescopic,
Rear suspension: Swinging arm,
twin shock absorbers/dampers
Wheels: 3.25 x 19-inch front,
3.50 x 19-inch rear
Maximum speed: 70-75mph
Royal Enfield G350 for 1951; the firm's first post-war single and easily mistaken for a post-war G2 Bullet. Except that post-war G2 (350cc) Bullets were never rigid framed. Also, the G350 carried its oil in a forward compartment in the crankcase, as opposed to a rear crankcase compartment on the G2. All the same, it was an understressed, easy-going ride with simple, rugged good looks. Just like the later Bullet.
1951 Royal Enfield 500cc twin;
essentially, a twin-cylinder Bullet. Note the pre-casquette headlight/speedometer arrangement. Image also details a sprung front mudguard
THE ROYAL ENFIELD BULLET is like a great stage show that just runs on and on, season after season, year after year, moving from town to town, continent to continent, easily understood and enjoyed by whoever’s gluteus maximus occupies the best seat in the house.
The secret of its success was nothing other than simple, sound and honest design coupled with ease of operation, ease of maintenance, good handling, decent braking, a strong parts supply, great fuel economy and (as ever) a highly competitive price. In today’s high tech multi-cylinder age, with variable valve timing, ABS and even two-wheeled drive, you might be forgiven for thinking that the most famous Royal Enfield of all has finally run out of ammunition. But the show must go on, and this show does go on, with sales of Indian built Bullets growing year on year and showing no sign of slowing up.
The Bullet name, which was perfectly apt for the Redditch, Worcestershire-based manufacturer of guns and ordnance, dates back to 1932 when Enfield introduced a range of OHV bikes of 249cc, 346cc, and 499cc.
These early, pre-war Bullets, with high compression engines, exposed valve-gear and rigid frames were, like most of the company’s product, solid and reasonably reliable motorcycles, conservatively styled and priced to compete head on with the offerings of the other major manufacturers of the day.
In 1936, a revised (all-alloy) Bullet appeared; a model that would set the rough shape for the Bullet as we know it today. And this bike, with minor revisions, continued in production up until the Second World War—at which time Royal Enfield was fielding no less than 20 models designed, it seemed, for every possible market niche.
▲ Post-war Royal Enfield advert. RE's bikes had served king and country well in WW2. But now there was a new battle ahead. A battle for sales to a population desperate for good value, reliable transportation.
In 1948, with the hostilities over, the Bullet concept took on fresh impetus when a prototype single cylinder 346cc machine arrived on the scene.
The man behind this G2 Bullet (and numerous other Enfields of that era) was Tony Wilson-Jones, a long time factory development engineer and mug-plugging rock-hopper of no mean talent. Wilson-Jones, through direct hands-on experience, knew exactly what made a good competitions machine and was prepared to take radical steps to get the bike he wanted, even if his kind of thinking was often at odds with the conservatism of the boardroom.
The two most significant features of the new 1948 bike were Enfield’s own brand of telescopic fork (two-way damped) and, more controversially, Enfield's own brand of swinging arm frame.
In itself, a swinging arm wasn’t a new idea. Respected designer Granville Bradshaw had, back in 1919, draughted a rear sprung chassis for ABC; and Matchless had launched its rear sprung Silver Hawk back in 1934. And then there was Vincent with its pivoted rear fork that the company championed to the bitter end (often against the advice of test riders and Vincent die-hards who increasingly felt that after two decades of leading the pack, the pack had taken a sudden turn and were now going off at a different, and arguably technically superior, direction).
▲1953 Royal Enfield Bullet.Spring frame, 19-inch wheels front and rear, Silver Grey Polychromatic enamel finish. Yours for £191. Plus change.
However, it was the trials boys who, in 1948, really put this G2 Royal Enfield Bullet through its paces, and that was where the … well, muddy stuff really hit the fan. Put simply, not everyone agreed that swinging arm was the way to go; not in that sport, anyway. The criticism was directed specifically at the poor damping of the early bikes that kept the rear wheel hopping “uncontrollably” as it bounced over the rough stuff. Until then, trials bikes had been rigid machines, favoured for their light weight and predictable handling. You didn’t so much hop and bounce over obstacles as muscle your way over them relying on exceptional throttle control, a perfect sense of balance, a cool head, strong thighs, and heaps of low down, grunting, gut-busting torque.
But Wilson-Jones’s new pretender needed a very different touch, which in turn demanded a radical change in thinking and handling, and Jones had a seriously hard time persuading motorcycle sportsmen (and Enfield’s own directors) that the age of the rigid frame trials bike was over, all bar the shouting.
Nevertheless, a select few riders worked hard to prove Enfield’s point, and almost immediately the competition notches began appearing on the company’s gun belt. And over the next decade, the Bullet, with its neat and compact rockin’n’rollin chassis, was a common and consistently formidable force on the muddy weekend killing fields of the home counties—leaving Ariel, BSA and Norton, and most of the rest of the competition, struggling on with their increasingly dated and uncompetitive plunger or rigid chassis, with Triumph alone clinging vainly to its unique sprung hub concept that had few friends and was amassing an increasing number of enemies.
▲ A terrific engine for a terrific bike. Simple to repair and easy to live with, the Royal Enfield Bullet is up there with the best of them—and the original UK build engines are as good as it gets. Highly tuneable too.
But there was more to the Bullet than a pair of big teles and a swinging arm.
The 350cc engine was a torquey little number that would become famed for both its “plodability” and its willingness to romp along when called upon to do so. It handled well on the straight too due in part to the “semi-unit” bolt-up Albion engine/gearbox that dramatically increased the torsional stiffness of the open (single downtube) frame. It was exactly those virtues, coupled with a short wheelbase, that made the Bullet such a hot piece of property in the hands of a top, or even average, trials rider.
Once again, a semi-unit bolt-up engine, etc, wasn’t a new idea. But it was a sound idea whose time had come and helped set the pace for full unit construction engines that arrived, in the most part, in the early 1960s.
At its heart, a 70mm x 90mm bore and stroke was contained in an iron cylinder deeply spigoted (recessed) into a vertically split alloy crankcase. The alloy cylinder head (also spigoted into the barrel) had its valves set at 90-degrees to each other and featured cast-in valve seats and a cast-in spark plug insert.
The built-up crankshaft (as opposed to a one piece unit) was keyed into polished steel flywheels. The assembly spun between a phosphor bronze timing-side (right side) bush, and two drive-side (left side) ball races (the timing side bush was supported by a caged roller race in 1951).
The con-rod was made from RR56 alloy. The big end was a white metalled bearing. At the opposite end pivoted a Lo-Ex (low expansion) alloy piston. Compression was 6.5:1.
A train of timing gears, driven by the crank pinion, ran backward up the right side of the engine terminating at the magneto drive gear, behind which a Lucas magneto fired the engine. The timing cover, meanwhile, was a highly distinctive and attractive design immediately identifiable as Royal Enfield (later ones featuring a small bulge to accommodate an optional automatic advance and retard unit). At the lower end of that cover, an oil filter housing was conveniently cast in.
A long time feature of Royal Enfield was the efficient double action oil pump (located in the timing chest) which provided excellent crank lubrication through drillings in the crankcase before being pressure fed to the main bearing.
Oil for these new engines was contained in a rearward compartment of the heavily finned crankcase (many earlier Enfields, note, carried the oil forward of the crankcase).
The primary chain was double row with a slipper adjuster to take up the slack (the engine sprocket and clutch hub centres were fixed due to the bolt-up gearbox design). The clutch was a fairly conventional wet, multi-plate unit that was both effective and reasonably light in action. The gearbox was typical Albion fare, being robust and predictable—if a little crude in application, and nothing if not “characterful”. In a worn gearbox, neutral could be found in a variety of places, most by accident. And if you were really lost among the cogs, a convenient/inconvenient neutral finder lever could be stamped upon that would take you back to the beginning from any gear except first.
In contrast to other manufacturers of the day, Enfield chose not to use an engine shaft shock absorber or, for that matter, a clutch centred shock absorber, but arranged to have a cush drive built into the rear hub. This was another old (Enfield) idea that dated back to before the First World War and worked well—albeit by compromising the ability to change the size of the rear wheel sprocket.
▲ 1953 Royal Enfield Bullet Scrambler sold by Bonhams in 2013. Click on the image for further details and a larger view.
Overall, the early G2 Bullet was a piece of quality engineering, well finished, well thought out—but never very well received. It sold poorly, eclipsed largely by rival machines from Triumph, BSA and Norton (et al) who were making better looking and faster products that, through numerous wins in a variety of road and track events, had captured the imaginations—and disposable income—of the important youth market who were still a few years away from a car.
Over the next few years, the 350cc Bullet underwent various revisions, notably to the lubrication system, and in 1953, the 499 cc (500cc) JS Bullet arrived. Its stroke was the same as the 350cc G2 Bullet at 90mm, but its bore was larger at 84mm (as opposed to 70mm). Almost identical to its smaller brother, the 500cc Bullet featured revised front fork legs with spindle lugs reworked for increased trail, thereby more suited to sidecar use. The 500 had in fact been available in 1952, but for export markets only.
That same year saw the introduction of the cast alloy “casquette” (containing top yoke, speedometer, headlight, and pilot lights).
There were changes to the Bullet’s engine breathing which, up until then, had been a timed system exiting through the crankshaft mainshaft into the primary chest before venting to atmosphere. The new arrangement, however, included an elbow on the drive side (left side) crankcase through which oil mist was directed to the drive chain.
Overall, the 350cc Bullet was upgraded to the standard set by the 500cc model.
In 1954, the Bullet’s gearbox end cover was reworked and simplified. Also, the gear lever and kickstart lever were now pivoting around a common axis.
Another important upgrade was the fitment of Armstrong shock absorbers/dampers which transformed the skittishness of the back end (previously supported by Enfield's less than adequate items) and gave a more taut and self-assured ride on both the flat and the bumps.
In 1955, dual seats, that had been optional since 1952, were standard fitment. The compression ratio on the 350cc Bullet was raised to 7.5:1 with a corresponding increase in horsepower (up from 18bhp to 19.5bhp—20bhp according to some accounts). The camshafts were also reworked for quieter operation. Frames were modified, most visibly around the shock absorber/damper units top mounts. Both bikes were given full width brake hubs. And the 350cc Bullet gained a new (ported) cylinder head with a larger inlet valve. Also, the exhaust header pipe was revised and was now a push fit instead of a push-over-stub arrangement. If that sounds like a retrograde move, the fact is that it worked.
In 1956, alternator electrics were introduced, but the two Bullets continued to run magneto ignitions. Also, both bikes were given dual 6-inch brakes.
That same year, the 500cc Bullet was given a taller—arguably less attractive frame. The swinging arm was also opened up to accept a larger rear tyre. Wheels were still the original 19-inches.
The 350cc machine was not neglected but was generally upgraded. Cooling fins were cast into the crankcases. The main bearings were changed, giving a ball race and roller on the drive side. And a double row roller was added on the timing side. The timing side plain bearing, incidentally, remained in situ.
For 1959, the most significant change for the 500cc machine was the introduction of the "big head" with integral rocker boxes and a downdraught carburettor. Enfield was making a genuine, if belated, attempt to grab a slice of BSAs Gold Star cake. Cams were revised and given a higher lift—which did little except make the engine (not unexpectedly) feel lumpier and prove that the Goldie was still living in unreachable territory (at least as far as Enfield was concerned).
Another questionable "improvement" was the fitment of 17-inch wheels front and back for the 350cc Bullet—which had previously rolled along on 19-inch rubber. The handling changed markedly making the bike less surefooted.
In 1960, the magnetos finally outlived their welcome (not least because Lucas was no longer interested in supporting them), and coil ignition arrived. The 500cc Bullet, meanwhile, reverted to dual 6-inch brakes at the front.
The following years saw few changes, probably because both machines were not long for the chop, and there was little sense in throwing good R&D money at what was rapidly becoming old hat. The company, in any case, wanted to move onto a new range of 250cc bikes,
By 1962, the 350cc G2 and 500cc JS, both of which had served the firm well for almost 15 years and had steadily, but never dramatically, clocked up sales, were taken out of production thereby bringing to and end the era of British made Bullets—notwithstanding a short-lived and unpopular new Bullet (in name but not in nature) built from 1963-1965 and based upon the firm's 250cc singles range.