1803 YD - Norton 1925/26 Model 18 Special 490 cc OHV Isle of Man racer - 1925 GB.

Like the majority of their contemporaries, Norton relies on the side valve engine until the 1920s, when the existing and well-tried 490cc unit is used as the basis for the firm’s first overhead-valve design. Penned by James Lansdowne Norton himself and first seen in prototype form in 1922, the overhead-valve Norton makes little impact in that year’s Senior TT, though at Brooklands D R O’Donovan raises the world 500cc kilometer record to over 89 mph using the new engine. For 1923 the OHV model is catalogued as the Model 18. At its introduction it gets the factory code word of “Speedy”, which certainly shows some foresight: speeds up to 100 mph are attainable with carefully tuned engines. In the course of 1923 a number of speed events are won, but in 1924 the Model 18 really shows what it is capable of. In June Alec Bennett wins the senior TT on a model 18 with an average speed of 61.64 mph; the sidecar TT is won by George Tucker on a 588 cc version of the model. Both the French and Belgian GPs are won by Bennett, which makes him the first man ever to win three major races in a year. Bert Denley captured the coveted British One Hour Record at 87.07 mph. In 1925 a redesigned drum brake and Webb centre spring forks are new features. In the Senior race Bennett opens up with a record lap and forges well ahead of the opposition, consisting of the very fast AJS models and Howard Davies on his JAP-engined HRD. By the end of the second lap a patch of oil on the road at Governor’s Bridge causes a tumble. This damages a footrest in such a way that it sticks into the ground on right-hand turns. Davies wins the race with Frank Longman (AJS) coming in second and Alec Bennett taking third place.
Copies of Norton factory records show that engine # 25300 (in frame # 17486) is built for the 1925 TT and intended for ‘A Bennett’. A special feature of this engine is that it has dry-sump lubrication, not used on standard Nortons at the time. Somewhat unusually, Bennett’s 1925