Royal Enfield Interceptor
Royal Enfield Interceptor Background & History
The Royal Enfield Interceptor as the company’s top line motorcycle, meant to compete with the likes of the Triumph Bonneville andNorton Atlas. It remained in production from 1960 to 1970. Royal-Enfield was an old company that, like BSA, started out as an arms manufacturer for the King of England. They got into motorcycles early and established themselves with a line of fast, reliable singles, like their 350cc and 500cc Bullet. But that all changed when Triumph introduced the world to the vertical twin in the form of the 500cc 5T Speed Twin. Suddenly everyone in the British motorcycle industry (who could afford it) rushed to bring their own vertical twin to market. Alas, World War 2 ended the fun until 1946 when civilian production resumed and Triumph was still in the lead with the Speed Twin and a new, high-performance stablemate, the Triumph T100 Tiger. BSA released their own twin, the A7 in 1946. Ariel launched their model KH in 1948. In 1949, Norton, Matchless/AJS and the Royal Enfield Meteor all came out with 500cc vertical twins, just in time for Triumph to trump them all again with the 650cc 1950 6T Thunderbird. Again the race was on, this time to turn their new 500s into 650s.
This 1963 Royal Enfield Interceptor 750 shows what a gorgeous machine they were.
Royal Enfield Interceptor Background & History
Royal Enfield trumped the whole bunch by bumping displacement not to 650cc like everyone else, but instead to 700cc (actual displacement was 692cc) in the 1953 Royal Enfield Super Meteor. In 1960, the company released the first bike named Royal Enfield Interceptor. It used a hopped-up version of the 700 Constellation engine. These engines had a prefix of “VAX” in their stamped engine numbers whereas the Constellations had a “VA” prefix. Legend has it that the added “X” stood for “experimental”. The new 700cc Royal Enfield Interceptor engine got dual carburetors, hotter R-grind cams, a lightened and dynamically-balanced crankshaft and a Lucas racing magneto with manual advance. Some weight saving was done on the bike itself. Despite all the specialness and the resulting power, it didn’t do well in the market with just 158 700cc Interceptors built in 1960 and 1961.
The Royal Enfield Interceptor 736cc (they called it a 750) motor was robust and powerful, and because of dynamic balancing, very smooth by British standards.
Series 1 Royal Enfield Interceptor
In 1962 the Series 1 Royal Enfield Interceptor was released with a 750cc engine (actual displacement was 736cc) by increasing the 70mm bore of the 700 to 71mm, and the stroke from 90mm to 93mm. But it wasn’t that simple, Royal Enfield did it right. They completely reengineered the engine with strengthened engine cases to handle the added torque, and nearly every other engine component was looked at and improved in some ways. And it must have worked considering the the claimed output was a whopping 60 hp at 6500 rpm. That’s 2 more horses than a 1969 Triumph Trident or a BSA Rocket 3! And the dynamic balancing that the factory did on the crankshafts of every Royal Enfield Interceptor made them one of the smoothest bikes on the road, certainly one of the smoothest British bikes. The Series 1 also got an automatic advance on the magneto and a new seat.
This 1963 Royal Enfield Interceptor 750 is a Series 1, also called a 'Mk 1' (Mark 1).
Royal Enfield Interceptor Series 1A, 2 & 3
There Series 1A Royal Enfield Interceptor was introduced in 1967 as two submodes, the GP7 and the TT7. The biggest change was the elimination of the archaic magneto in favor of a modern points-and-coil ignition system. US models got a new chrome tank, new seat, new instrument mounts, handlebar and fenders. Twin carbs were changed to Amal Mark 1s.
The Series 2 Royal Enfield Interceptor saw a major redesign of the Series 1A engine. New was a wet sump lubrication system, a rare thing for a British motorcycle. The contact points were moved to the end of the exhaust camshaft and the timing cover was reworked accordingly. This engine remained in production until the end of Royal Enfield of Reddich, England (not to be confused with the Royal Enfield company in India) as a company in 1970. Even after Royal Enfield ceased making motorcycles, a market remained for these Series 2 engines from custom and low-volume motorcycle makers like Floyd Clymer and the Rickman Brothers.
The Series 3 Royal Enfield Interceptor never moved out of the prototype phase. It was to be called the 800 Interceptor (with 778cc of actual displacement). However, the Royal Enfield factory and company closed before the project could come to fruition.
1963 Royal Enfield Interceptor 750 engine, primary drive side.
Royal Enfield Interceptors from India
In 1952, when the new government of India tested several motorcycles to fill its need to patrol it’s huge borders, they found the Royal Enfield 350 Bullet to be the most suitable. By 1955, Royal Enfield was not only selling them motorcycles, they partnered up with Madras Motors to form a new entity, Enfield India, to assemble Bullets under license in India from British-made components. Over the next few years the British company sold more and more of the tooling needed to build the bikes until in 1962 the Indian Royal Enfield was now producing motorcycles entirely in-house. That Indian company survived the original English one and is thriving today, still building Royal Enfield Bullets just like they used to, and more recently a whole new line of twins. In 2018 Madras, now called Chennai, announced a line of 650 twins that included the Royal Enfield Interceptor 650.
This is the 2024 Royal Enfield Interceptor 650, built in India.
Royal Enfield Interceptor Books
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