An enlarged version of the
350 engine was produced for the Dart. Despite the increased capacity
this engine was in fact less powerful. Aimed at the Japanese home
market it had small exhaust ports, deliberately restricting power.
A German company; AMEX
(Alexander Motor Export) unhappy with the styling of the K2, built
bikes with the earlier styling. They used the 400 engine as well
as 478 and 507cc versions of the 500. Quite what state of tune these
engines were in is unclear although they were supposed to have
different camshafts and other modifications.