Bad vibrations shouldn’t occur on a Rickman Interceptor as reported by Alan Cathcart in RC194. Dynamic balancing of each crank with weights attached to represent the conrod and piston assemblies was good practice to address the small differences arising from sand casting. The result was one of the smoothest big twins available, evident from a lack of rubber fixings on either the Rickman or the Redditch Interceptor.
The motor of the test bike may have lost its balance from the use of heavier or lighter replacement pistons, but there is another possibility. It’s been said that the motors built for the Floyd Clymer Indian Interceptors (most of which went into Rickman bikes) had a different balance factor to those of the original Royal Enfield. This incompatibility of motors could be more than an urban myth, realised from the boxes of parts which made the Pennsylvanian test bike. Oily Boot Bob, member
Interesting. I’ve ridden several Series 2 Interceptors and every one of them shook to a greater or lesser extent. My first-ever paid-for roadtest was a double feature of an RE Series 2 with a Matchless G15 Mk2, which had an Atlas engine. The Matchless was the smoother.