Why did AMC make their own engines ?
After years of good service from Villiers units it is hard to understand why AMC decided to go it alone. The development costs must have been significant. They had two ranges of motorcycles (James and Francis-Barnett) in which to use the motors and they had the casting, forging and machining facilities to do the job at Plumstead. Nevertheless it was a considerable undertaking, which they staggered over the 1956 – 1959 period, and it probably did not bring the rewards they had hoped for. In “Motor Cycling for 18 October 1956, in a write up of the new 250cc 25T engine the reporter writes that the decision to make their own engines was “…not just an expeditious alternative to the proprietary units hitherto employed in the AMC-Group lightweights, but a serious attempt to equal, if not surpass, Continental two-cycle design.” I think time will suggest that they did not succeed. In the end they contracted Villiers to assemble (and probably develop) the engines.
