Rare overhead cam AJS
The first weekend in November I attended the Jampot Rally at Kelso near Bathurst. There was the usual roll up of twin and single AJS Matchless motorcycles including some nice looking Competition Models. However one different machine caught my eye and appealed to me the moment I spotted it. It was a 1929 M10SR 500 OHC owned and built by Rob Smyth from South Australia. He was there with his son Michael who was riding another of Rob’s machines, a 1924 B1 350 which Rob purchased in 1958 for one pound.
It transpires that Rob was an Electrical Technician working at the South Australian Institute of Technology which later became the University of South Australia. He explained to me that the letter M indicates that the machine is a 1929 model, 10 is 500 OHC, S for Special and R for Racing. His machine was originally stamped No.5. When raced it was fitted with a sidecar and raced by Alex Ridgeway in both scrambles and short circuit meetings. It had a major engine blow up in the late 1940s or early 1950s and never rebuilt. Chris Harley gave Rob some parts and agreed to give more once he saw that he was undertaking a rebuilding task.
These parts initially consisted of two crankcase halves and a couple of heads. The crankcases had been cracked vertically and required extensive welding. A later model feed oil pump was fitted which then required Rob to make a new scavenge pump which lubricates the cam chain. There were no flywheels, pistons or valves. Steel Red Hunter flywheels were fitted which gave a 95mm stroke and 83 mm bore. The original engine would have been 101 ml stroke with a 79 ml bore. The petrol tank was located in Broken Hill and the rear 21 inch rim in Mildura. The racing machine would have had a four speed gearbox which was unable to be located so a 3 speed close ratio from another 1929 model AJS was fitted. Rob tells me that this was the last year that AJS actually made their own gearbox. This machine is fitted with a nine inch rear and an eight inch front brake which is correct for the original specifications. He used a modified M8 frame. The original M10SR frame had a third strut going from the back axle to the rear of the engine under the gearbox. This project took several years before it was completed in 2000. He has ridden this motorcycle in a number of rallies during which time it has clocked up some 27,000 miles. Rob took it to show Alex Ridgeway who then produced a photo of this machine in racing trim. Alex has since passed way. Rob tells me that he is aware that there is also one of these machines being restored in Tasmania.
This machine is a credit to Rob’s engineering skills and ability and shows how somebody with dedication can make such a nicely presented and reliable motorcycle when they had so very little to commence with.