1970 ROYAL ENFIELD INTERCEPTOR BACKGROUND Royal Enfield hopped up its 692cc Constellation and created a new model, the 700 Interceptor in 1960, for sale in the US and Canada markets only (on England). They’d just lost their contract to rebadge Constellations with Indian Motorcycle regalia then selling them in the US (or trying) as the Indian Chief. It wasn’t a great plan from the start, and from 1955 to 1960, far fewer bikes were sold than needed to be to ensure profitability. So now that all that factory capacity was freed up, the filled that gap with a new top-line model, the 1960 700 Interceptor. By 1962, they’d bumped displacement to 750, as it stayed until the last Interceptor rolled off the assembly line in 1970. At that time, ailing, struggling Royal Enfield sold all its assets to Madras Motors of India, who moved production to India, and still builds the single-cylinder Royal Enfield Bullet to this day.
1970 ROYAL ENFIELD INTERCEPTOR TUNING SECRETS
Royal Enfield felt they needed to do something meaningful if they were to overcome the bad reputation that the Indian debacle had cost them. So, when it came time to replace that bike with one of their own marque, they went all the way with performance modifications over the old Constellation upon which the Indian Chief was built. These were already very strong engines, one of the only British vertical twins with a center main bearing, aiding not only its bottom-end strength, but also its smoothness. First off the old 692cc Constellation engine got 2 carburetors instead of one, a lightened and balanced crankshaft, hot “R-grind” cams, and a Lucas magneto. Displacement was increased to 736cc in 1962.