The Gradua system simultaneously changed the diameter of the crankshaft belt-drive pulley to alter the drive ratio, while moving the rear wheel forward or back to maintain belt tension.

[3] The Gradua's action was controlled by a rotating lever atop the fuel tank, and was among the first attempts to provide multiple drive ratios for a motorcycle, at a time when very simple, direct belt-drive transmission was the industry norm.

Zenith motorcycles used engines from various suppliers including Precision, Villiers, Bradshaw, Martlett, British Anzani, Fafnir, and JAP.

[12] The ex-Zenith works rider Joe Wright, riding an OEC with a 994 cc (60.7 cu in) JAP engine, took back the record on 31 August at 137.23 mph (220.85 km/h), again at Arpajon, France.

[11] Claude Temple made arrangements to try to win the title back in Cork, Ireland using his supercharged OEC again with Joe Wright on board.

[13] Joe Wright had managed to acquire the works 995 cc (60.7 cu in) supercharged J.A.P-engined Zenith, and he took this to Ireland as a spare machine (visible on the Pathe news when the OEC is tow started[13]).

The OEC bike suffered a mechanical failure and was not able to complete the required two runs, so Wright used his Zenith to set a new world record of 150.65 mph (242.45 km/h).

[17] The Zenette motorcycle had another instantly recognisable feature, the fuel tank and battery were at the rear of the engine space, leaving a bare top tube.