In our shed

Your feature suggesting a Dave Curtis Matchless should be in our shed caused a lot of interest for us as while we don’t have one of Dave’s bikes in the shed we believe we have three-quarters of the famous 600cc Matchless engines that won many national scrambles

This engine is not the one used in a bike Dave Bickers rode and subsequently passed on to the Rickmans but a one-off works motor. The photo enclosed shows the barrel flange shortened by 7mm and one fin machined from the top of the barrel thus reducing it by a further 12mm. Other features include a central plug and a cutaway for a side plug. Inside the engine are 7R/G50 flywheels and con rod which gives a stroke of 96mm. The cylinder head has 1 13⁄16in inlet and exhaust valves and a small slot for a racing spark plug too.

The story goes that the engine was fitted with a massive piston, likely a 90mm bore G50 one giving it a capacity of 610cc. In Don Morley’s ‘bible’ – Classic British Scramblers – he mentions it was tried without a main jet fitted, which sounds like it was on dope. Don also mentions the motor was shorter but this is likely the other motor that was built for Curtis using all G50 internals and it was this motor that was passed to the Rickmans and subsequently passed to Pat French.

Our motor came to New Zealand from the AMC comp shop in the early 60s but when it was being overhauled by having a new sleeve fitted to the barrel the alloy split during the pressing operation. The engine wasn’t used after this and was still in this condition when we bought it. We rebuilt it and fitted a shorter barrel and a G80 piston, which brought the capacity down to 570cc. We know the engine was used from about 1958 to 1960 and would love to find Mortons Archive has a pic or two showing it being used in National scrambles.