J A Prestwich founded his company in 1902 and for the first four years most of his engines were sold in his own motorcycles but from then on and in increasing numbers other manufacturers began to use them and for good reason. JAP engines were rugged, durable, simple and were very powerful. 

In 1912 HFS Morgan’s three wheeler was announced with a JAP engine and it soon became clear that these remarkable little three wheelers were much faster than cars of equivalent horse power, they were ideal for various forms of competition and they won all sorts of events. They were also the first un-supercharged 750cc cars to lap Brooklands at 100 mph; they had beaten MG by a few months. 

There were motorcycle successes too: In 1922George Brough built his sprint and Hill Climb special “Old Bill”, with a JAP 4 cam side valve engine and won 51 firsts in a row on it! Not surprisingly he chose a V twin JAP engine for his magnificent SS100 motorcycle as well as other models in his range. Brough Superiors were justifiably regarded as the Rolls-Royce of Motorcycles. A JAP engined Grindlay Peerless was the first 500cc bike to lap Brooklands at over 100 mph and in 1930 Barry ECE Baragwanath built a Brough Superior with a supercharged JAP V twin in it and Noel Pope rode it to break the sidecar lap record at 106mph and the Solo at 124mph!

By 1929 JAP engines virtually monopolised Speedway and Grass track racing and continued to do so until the nineteen sixties!

After the Second World War money and resources were scarce so John Cooper and a few others produced tiny rear engined racing cars that had 500cc Jap engines and motorbike gearboxes fitted to them. They provided spectacular racing and some extremely famous people including Stirling Moss began their career with them and it wasn’t long before some Hill Climbers were fitting them with 1000cc V twin engines of which some were supercharged and very fast indeed. 

JAP engines make the most vicious staccato crackle, it’s a spine tingler and gives them real charisma, and many are still actively campaigned in all sorts of Historic Motor sport today. If you use one, Cameron Racing Engines can build yours or supply you with parts to do your own and we can mend, make or set your chassis up for the best possible results. 

On the contacts page you will find links to numerous websites where you can read much more about JAP engines and the vehicles they powered.