The 1974 Triumph Bonneville was built in very low numbers. It was a very odd year in Triumph Bonneville history. Angry workers hearing of the impending shutdown of the Triumph Motorcycles plant at Meriden, shut it down themselves in protest, in October 1973 just as production was being switched from 1973 models to making 1974s. This affected not just Triumph Bonneville production but also Triumph TR6, TR7, & Triumph Daytona (Tridents were produced at BSA’s Small Heath plant, side-by-side with BSA Rocket 3s). Production didn’t resume again until 1975, so very few 1974 Triumph Bonneville s were ever produced.
However, the 1974 Triumph Bonneville model year did begin officially with Engine #GJ55101, but since so few bikes were actually built, the usual rash of mid-year revisions never happened. As the result, one of the very few changes made to the engine were new rocker boxes with two extra bolts on each inspection cover. The slimline tank grew from 2-1/2 US gals to 3.6 US gals. Other than minor detail changes here & there, the only other significant difference from the previous model year was the color schemes, now Cherokee Red over Cold White with Gold pinstriping for the T140, and Purple over Cold White on T120s. Again, the fenders were chromed & only the tank was painted.