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Is the huge horse power difference between the Thruxton/Bonnie and the Speedy/America/Scrambler due to the firing interval or there other factors at play? Compression and displacement are identical but the thruxton is listed at 69 HP and the Bonnie 66 while our bikes are down to 54 HP. Are there other differences or is that it?


I'm supposed to be working, so I don't have my book, But I think the differrence is more cams than crank difference. The Thrux gets its power at higher RPMs, less bottom end torque. Different cams, cam timing.