Starmaker engines and Stormers were supplied with different primary and gear ratios depending upon engine size and the intended use for the motorcycle. Starmaker engines were supplied as 250 Trials, 250 Scrambles or 250 Road race engines. From 1967 on, Villiers also supplied a unique 6 speed gear box for road race use. (not covered here)
You can use the charts below to compare each 4 speed gear box. Gears are interchangeable from all years of manufacture. We have stock of all the WR and CR gears only.