The 1926 Lightweight TT Race produced one of the most notorious events in the history of the Isle of Man TT Races, described by the "The Motor-Cycle" Magazine as the "Guzzi Incident." The Italian rider Pietro Ghersi was excluded from second place for using a different sparking-plug in the engine of his Moto Guzzi. Despite the competition from the Italian marques the 1926 Lighweight TT Race was won by 'Paddy' Johnston riding a Cotton motor-cycle, in 4 hours, 23 minutes and 16 seconds, at an average speed of 60.24 mph for the 7 lap race.
The 1926 Senior TT Race was less controversial and was won by Stanley Woods riding for Norton for the first-time by 4 minutes from Wal Handley. The 1926 Senior TT Race produced the first 70 mph (113 km/h) lap and was again set by Jimmie Simpson on an AJS motorcycle in 32 minutes and 9 seconds an average speed of 70.43 mph.