At the beginning of the 1920s the Collier brothers designed a 350cc OHC engine with the intention of fielding three machines in the 1923 IOM TT Junior class. Development did not go according to plan and Blackburne engines were instead used in the Matchless frames.
The design of the OHC engine evolved through three different models until production ceased in 1929. The cylinder head had a hemi-spherical combustion chamber with large diameter valves and the camshaft drive was located on the rear RHS of the engine block driven by straight-cut gears and a bevel-geared shaft to a second pair of bevels connecting the camshaft in the head. The camshaft was running at right angles to the crankshaft and the inlet and exhaust ports were on the right and left side of the engine.
Of the three machines entered in the 1926 Tourist Trophy none finished*. Only one suffered a mechanical failure, and the best placing during the race was 12th.
The design had several distinctions from the classic design adopted later by Velocette, Norton and others. With the vertical bevel-geared shaft mounted on the rear of the engine rather than on the crankshaft extremity, it was necessary to closely monitor the crankshaft end-play. To achieve half engine speed a train of straight cut gears was employed allowing the bevel gears to be all of the same size, and their bearings could be considerably larger than if the vertical axis was on the side of the engine.
While the bikes had some success in endurance trials, including 3 Gold medals in the ISDT (International Six Days Trial) of 1926, the failure of the three machines in the TT of 1926 would have been quite demoralising for Collier & Sons, especially as the Velocette 350 OHC piloted by Alec Bennett finished a good 10 minutes ahead of the field. The successes of Velocette accumulated, winning the TT again in 1928 and 1929. The "Cammy Velo", which the Goodman firm marketed as the first "over the counter" production racer, became the must-have for the sporting rider of the period.
Although the design of the Matchless engine was advanced, the wet-sump lubrication system of 1924 was crude and the cylinder head was still running exposed valves which lacked pressure-fed lubrication. Even in the final version the oil feed left much to be desired in comparison with the competition's dry sump systems.
With the carburettor mouth thrust boldly into the airstream sucking anything proferred, with inadequate brakes and a reputation for finishing well down the field if at all, the model was not fondly considered by the sporting community. Sales were slow.
1928 Matchless L/R2 Specifications
Engine: Single Cylinder OHC
Capacity: 347 cc
Bore/Stroke: 69 x 93 mm
Compression ratio: 6.04:1 (standard) or 7.21:1
Power: 16.5 HP at 5,000 rpm
Ignition: Lucas HT Magneto
Gearbox: Sturmey Archer 3 Speed
Suspension: Matchless parallelogram forks front, rigid rear.
Tyres: 3.25 x 19"
Brakes: 8" drums F&R, both foot actuated.
Weight: 225 lb (102 kg)
Fuel tank capacity: 2 gallons
Fuel consumption: 95-115 mpg
Maximum Speed: 70/75 mph (claimed)
* 1926 TT results: Todd (Matchless), broken handlebars, retired lap 1. Barber (Matchless), engine failure, retired lap 4. Scott (Matchless), burst petrol tank, retired lap 5.