In 1960, Royal Enfield introduced the first motorcycle bearing the name Interceptor. It had a tuned version of the company's biggest engine, the 692 cc vertical-twin and was only sold in the US and Canada. All engines had the engine prefix letters "VAX" and so these are often referred as "VAX Interceptors". The then flagship 692 cc 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 carburettors, except for some early models; a factory lightened and balanced crankshaft; high-performance "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 lights, etc., offered when Enfield failed to sell enough motorcycles in the standard scrambler trim. A total of 158 692 cc Interceptors were made, according to the despatch ledgers from the
Redditch factory, now held by the Royal Enfield Owners' Club in the UK. All of these machines should have been stamped with the VAX prefixed engine numbers. The maximum possible number of 692 cc VAX Interceptors is 170. The first examples left the factory in December 1959, and the last were despatched in July 1961. ==Series 1 Interceptor==