Interstellar Overdrive: 1959 Royal Enfield Constellation

Cycle makers caught the fever too: BSA made the Star Twin and Road Rocket; Vincent built the Comet and Meteor; and Royal Enfield’s performance twin of 1958 was named for patterns of stars in the celestial sphere: Constellation.

Space race

It seems to be a little-known fact that for 10 years, Royal Enfield made Britain’s biggest capacity parallel twins. The 693cc Super Meteor and Constellation held the title from 1953 to 1962, when Norton launched its 750 Atlas. (Enfield came back with the 750 Interceptor.) And like most of the other British twins (BSA being the exception), Enfield’s bigger banger started out as a half-liter. The prosaically named 500 Twin first appeared from RE’s Redditch, England, factory in 1948. And while it aped many of the characteristics of the other British parallel twins, it had some exclusive Enfield features.

The vertically split engine cases included a separate compartment holding four Imperial pints of engine oil, creating a dry sump engine with an internal oil tank. The oil was circulated by Enfield’s unique reciprocating, double-acting piston pump with a replaceable felt filter. The two separate (and interchangeable) iron cylinder barrels of 64mm bore had extended sleeves that were spigoted deep into the crankcase. Each was topped with a light alloy cylinder head, fed from a single Amal 276 carburetor.

The iron crankshaft ran on a roller bearing/ball bearing combination with two plain big end journals giving a stroke of 77mm. Light alloy connecting rods with split big ends ran directly on the crank, thus making the rods “disposable” when worn — a practice shared with Triumph. Like Triumph’s twins, the Enfield used two camshafts, but driven by a single chain instead of gears. The cams were removable through the primary side without splitting the cases via a pair of circular access plates. The pushrods, one at each corner of the engine, operated the four valves via rockers, each accessed by an alloy cover.

Unusual for the time was the Enfield’s ignition system. Instead of the usual magneto was a coil ignition system fed by a 6-volt battery charged by a DC generator. Contact breaker points were mounted inside a distributor driven off the generator.

In typical Enfield fashion, the 4-speed Albion gearbox bolted right to the back of the engine — known as “semi-unit.” The frame, front and rear suspension and cycle parts followed the same year’s Bullet single pretty closely, including a similar open loop frame. It’s worth noting that Enfield (along with AJS/Matchless) was one of the first to use swingarm rear suspension, six years before BSA, Norton and Triumph. The 500 Twin was smooth and reasonably quick, weighing 390 pounds dry and making 25 horsepower, giving it 85mph potential, according to period reports.

Mighty Meteor

The Constellation’s progenitor, the 693cc Meteor, was launched in 1953. And because Enfield was never a high-volume manufacturer, the factory did what it could to minimize proliferation in the parts bin.

Whether or not its 693cc engine capacity was chosen to keep the Enfield Twin ahead of its 650cc competition, the choice had technical and production merit. The 70mm bore meant the engine could use much of the top end technology of the 350 Bullet, including the pistons and combustion chamber design.

The Meteor’s 90mm stroke was also borrowed from the Bullet, conveniently being about the maximum that could fit in the existing 500 Twin crankcases. To improve braking performance, the existing 6-inch drum front brake was “twinned” instead of producing a new item of larger diameter. The rest of the Meteor mostly echoed the 500.

For 1954, Enfield’s new “casquette” (French for “cap”) was fitted to both the 500 and Meteor. This alloy casting formed the top triple-tree and contained the headlight, instruments and switches. A new frame with dual loops behind the powertrain was introduced for 1955, and for 1956 a compression increase from 6.5:1 to 7.25:1 and bigger valves boosted the Meteor’s output from 36 to 40 horsepower. Magneto ignition and an alternator replaced the DC generator/coil system. And it had a new name: Super Meteor.

Reaching for the stars

Competition among the Big Three British makers was heating up in the late 1950s, with BSA and Triumph’s flagship models, the Super Rocket and Tiger 110 making 46 and 42 horsepower, respectively. Norton’s 49 horsepower 650SS was waiting in the wings, as was Triumph’s 46 horsepower Bonneville.

Royal Enfield responded with one more power boost from the 700 engine when the Constellation arrived for the 1958 season. Based on the Super Meteor, compression went from 7.25:1 to 8.5:1, and it had hotter cams, a siamesed exhaust system, and an Amal 10TT9 racing carburetor. Crankshafts were dynamically balanced at the factory to minimize vibration.

The engine now produced around 50 horsepower at 6,250rpm, driving the Albion 4-speed gearbox with its extra neutral-finder lever through the “scissor” clutch adapted from the Meteor Minor. The Constellation used the same frame and running gear as the Super Meteor, but replaced the painted fenders with chrome-plated steel blades. The new 4-1/4 Imperial gallon (5 gallon U.S.) gas tank was also chromed, and featured a broad top panel finished in “polychromatic burgundy” with gold pinstriping. It looked fast — and it was, with a top speed of 115mph according to a 1958 Motor Cycling magazine test.

As the class horsepower leader, the Constellation should have been a good choice for production racing, but the promise was never fully realized. Constellations were usually the fastest bikes in the field, but frequently retired with mechanical issues. The closest RE came to a significant victory was in 1958, when Enfield dealer Syd Lawton entered a Constellation in the 500-mile endurance race at Thruxton circuit with riders Bob McIntyre and Derek Powell. Though they recorded faster times on the track than the eventual winners (Mike Hailwood and Dan Shorey on their Triumph 650), McIntyre and Powell lost time in the pits, handing the race to their rivals.

For 1960, a pair of 30mm (1-3/16 inch) Amal Monobloc carburetors replaced the racing TT carb. The tight fit behind the engine meant no room for the right-side carburetor’s float bowl, so both were fed from a single float bowl on the left side. Forward pointing “ears” were added to the side panels at the same time.

As was the fashion at the time, the Constellation got some body panels around the rear wheel for 1961 and a new, flatter dual seat. But the big news from Enfield in 1962 was a new model with one more stretch for the twin. Bore increased 1mm to 71, while the stroke grew 3mm to 93 for a capacity of 736cc. The Interceptor would remain in production in various forms until Royal Enfield’s final demise around 1970.

The final iteration of the Constellation was in 1963. With production of the Interceptor in full flow, the Constellation was repositioned as a sidecar tug, with the Super Meteor-spec 7.25:1 compression 40 horsepower engine, coil ignition, big fenders, steering damper and revised “sidecar” fork moving the front axle farther forward. But by that time the sidecar market was dead, and the Constellation died with it.

Tony Cording’s Constellation

As Western (and briefly National) Sales Manager for Yamaha for 25 years, Tony Cording always had motorcycles front and center. His first bike at age 15 was a 1939 Matchless-powered OK Supreme, followed by a 1936 Series A Vincent single, “The one I really wish I still had,” Cording says.

As a 16-year-old bike nut in Britain in the 1950s, Cording had a top-five wish list: Top was a Vincent Black Shadow, then a Norton Dominator, followed by a BSA Road Rocket, AJS 650CSR — and a Royal Enfield Constellation.

Migrating to Canada at age 24, family then took priority until 1975 when he acquired the first of a number of Vincents — a series D Rapide. That was followed by a D Black Shadow and a Black Prince. Next came a Comet basket case that, with help from now-deceased John MacDougal, was turned into a replica “Grey Flash” racer. His current daily driver is a hybrid series C/D “Super Sport” Comet with a 636cc engine.

“I managed over the years to acquire Vincents and the Dominator, but the Royal Enfield was one I never expected to see in Canada because they were never a very popular motorcycle,” Cording says. Then a couple of years ago, Cording shared his wish list with Vancouver vintage bike master builder Dan Smith. “I said, ‘I’ll never find a Royal Enfield.’ Well, within two weeks, he’d found me one!”

The Enfield he found at the home of local Enfield guru Bob Wheeler was an early Constellation, dismantled and essentially a basket case. “I knew nothing about Royal Enfields, except the fact that I’d always wanted one.” A deal was done. Then Cording took stock of what he had bought.

“I picked up a matching frame and engine number. I didn’t realize at the time the gearbox had to match as well. The engine was in a state of significant disrepair. And there was a frame, wheels, tank, handlebars, and basically that was it.”

The engine had thrown a rod at some time, wrecking one cylinder and smashing the exhaust camshaft oil gallery. Remarkably, someone had welded the cylinder skirt back together! “Like a jigsaw puzzle. The guy must have done some very, very careful welding.”

Deciding that cylinder had to go, Cording found another one on eBay, and set to work on the rest of the engine. The crankshaft was reground and the cylinders bored to 0.040-inch oversize, and the crankshaft was dynamically balanced, as Royal Enfield did at their factory. Another Enfield feature — the crankcases were coated inside with a sealant to prevent oil migration. “I’m surprised that other companies didn’t do that,” Cording says. The liquid coating is highly flammable, so sourcing and shipping it was a challenge. Finally, after numerous attempts, Cording found a supplier in Canada — less than 10 miles away!

Cording was impressed with the size of the main bearings — “they’re monsters!” — and with the way the camshafts can be removed and replaced through access holes in the primary-side without splitting the cases. “It was a delightful engine to put back together again,” Cording says. “And because they’re separate cylinders, I didn’t have any problems getting the barrels on.” However, for the gearbox, Cording turned to Vincent expert Robert Watson. “He put the gearbox back together again. And as has been commented on many occasions about the Albion gearbox, it is very agricultural, but very, very, strong.”

For originality, Cording stuck with Enfield’s notorious “scissor” clutch: “If I’d decided to go with the later style clutch, I’d have to buy a new gearbox,” Cording notes, “because the scissor clutch gearbox doesn’t lend itself to the (later) pushrod arrangement.”

Cording’s research shows his bike was one of 10 Constellations brought into Canada in 1959, nine going to Montreal and one to Toronto. And while the U.K. Royal Enfield Owners Club provides a dating service, confirming Cording’s bike to be a ’59 Constellation, they have no records of which bikes went where. The plot took a twist when Cording discovered a stock Constellation seat and gas tank didn’t fit the frame. It turned out the Constellation had been set up as an Indian Apache, the U.S.-market version of the Connie with wider wheels, a smaller gas tank and a larger seat. “By this time, I was so far down the road into making this a Constellation, I carried on,” Cording says. Unanswered still is whether the bike was shipped as a Constellation and modified once in Canada, a possibility as the only modification required to make it an Apache was the welding on of a different seat bracket followed by fitting an Apache-spec seat and gas tank.

Another odd aspect of Cording’s Connie: The frame had been chrome plated. That suggested it may have been a show model, but more research showed that the chrome had been added later, not applied by the factory. “It’s a really nice job. The more I worked on the bike and looked at it with the chrome, the more I liked it. I made the decision to keep it chrome. And with the nice chrome on the tank, it has all worked out quite well,” Cording says. The tank itself is a new item from India. “The finish was perfect, though there was rust inside.”

Most other parts for the project came from Royal Enfield specialists Hitchcocks Motorcycles in Solihull, England. “Hitchcocks were wonderful. Their website and parts availability was top notch. Their responses to my inquiries were always prompt.”

The only other challenge in the build was removing the seat nose bracket that had been added to the Constellation frame to suit the Apache seat and gas tank. Otherwise, Cording says, “It was so straightforward, it was amazing. It really was a lot of fun to work on. Getting the pushrods in, where you’ve got the camshafts at the front and back of the engine — that was a lot easier than on a Norton, I’ll tell you!” MC

Indian Summer: American Indian Enfields

After Indian went bust in 1953, Britain’s Brockhouse Engineering bought the rights to the name and started supplying English motorcycles to the Indian dealer network. What would be more logical than to turn them into Indians to take advantage of the name recognition?

So Brockhouse produced the Indian Fire Arrow 250 (based on the RE Clipper), 150 Lance (Ensign), Woodsman and Westerner (Bullet), Tomahawk (500 Twin) and Trailblazer (Meteor/Super Meteor), shown at left in a 1958 Cycle ad. Introduced around the same time was a new model, the Chief, based on the Trailblazer, but with 16-inch wheels and available in full police trim.

Brockhouse sold out to AMC in 1962, which preferred to sell Matchless models as Indians instead. So the trickle of Enfields into the U.S. ceased, except…

AMC went bust in the mid-Sixties, and the Indian name passed first to Berliner Corporation, then to Floyd Clymer. Clymer had always wanted to revive the Indian brand. His first attempt was a new V-twin Scout through a partnership with Friedl Münch of Mammut fame. Then came a batch of Velocette-engined machines using Italjet frames and cycle parts. Finally, Clymer agreed to buy a batch of Interceptor engines from Norton-Villiers, who then owned Enfield. When Clymer died in 1970, just a couple of prototypes had been built with the Italjet chassis, with the remaining batch of engines still in the U.K. The Rickman brothers, Don and Derek, bought the engines and fitted them into Rickman Metisse frames, creating the now-rare and desirable Rickman Interceptor.