Royal Enfield Interceptor

Manufacturer	Royal Enfield
Production	1960–1970
Engine	692 cc/736 cc air-cooled overhead valve parallel-twin
Top speed	115mph
Power	52hp
Transmission	500
Weight	410 pounds (190 kg) (wet)

The Interceptor was a British motorcycle made by Royal Enfield between 1960 and 1970. The 700 Interceptor introduced in 1960 was a modified version of the company's 692cc Constellation twin. In 1962, the company introduced the 750 Interceptor which evolved constantly till the end of production in 1970. ^[1]

700 Interceptor

In 1960, Royal Enfield introduced the first motorcycle bearing the name Interceptor. It had a highly tuned version of the company's biggest engine, the 692cc vertical twin and was only sold in the USA and Canada. All engines had the engine prefix letters "VAX" and so these are often referred as "VAX Interceptors". It may be noted that the then flagship 692cc Constellation had the VA engine prefix(on the US export model) and "X" was added to denote that Interceptor had an experimental engine. They had twin carburetors (except some early bikes), a factory lightened and balanced crankshaft, hot "R" cams, Lucas racing magneto with manual advance and a few other weight saving modifications compared to other Royal Enfield models. There was also an Interceptor "S" (Sports) model with "highway trim" -- quick detachable(QD) lights etc, offered when Enfield failed to sell sufficient quantities of bikes in the standard scrambler trim. 163 bikes are made as per the Redditch factory despatch ledgers held by the Royal Enfield Owners Club in UK. The very first bikes left the factory in December,1959 and the last ones were despatched in July,1961. The engines in the highly tuned form demanded proper maintenance more than similar 692cc models and many ended with catastrophic damages to the bottom end. Only a handful of these bikes survived which makes them one of rarest post-war Royal Enfield models.^[2]

Series 1 Interceptor

Royal Enfield introduced their all new 736cc twin cylinder engine in 1962 on the 750 Interceptor. Bore X Stroke was 71mm X 93 mm. The new engine was similar to the 692cc engine; but there was hardly any part that was not modified or improved. 750 engines are known for their reliability and torque. The engine cases were beefed up to withstand the increased torque. What sets this engine apart from other contemporary British twins is that the crankshaft was dynamically balanced from the factory which made these bikes one of the smoothest British twin engines ever. The Series 1 bikes had an automatic advance magneto, coil ignition, new seat etc. There was a rare single carburetor model as well. It was made till 1966.

Series 1A Interceptor

The Series 1A Interceptor was introduced in 1967 with two sub models GP7 and TT7. The major change was the introduction of coil ignition, eliminating the magneto. The US models received a new chrome tank, a new seat, instrument mounts, handlebar, fenders etc. ^[3] All S1A interceptors had twin Mark 1 Amal carburetors. The breather system was modified to eliminate most of the oil leak problem that plagued the Royal Enfield twins since the 1950s.

Series 2 Interceptor

The Series 2 Interceptor engine was a major redesign of the Series 1A engine. The S1A engine was modified to a wet sump engine to make up for poor oiling of the crankshaft. The CB points were moved to the end of exhaust camshaft and the timing cover was redesigned accordingly. This engine was used on the Interceptor till the end of production in 1970. This engine was later used on Rickman Interceptor and Clymer Enfields.^[4]

Series 3 Interceptor

Royal Enfield made a prototype Series 3 Interceptor to replace the Series 2. The bore was enlarged to 73mm to increase the engine capacity to 778cc; it was called the 800 Interceptor. However, the company went bankrupt before mass production was realized. Steve Linsdell owns the original prototype as of 2011.

References

See also

• Honda Interceptor