The main clutch spring is a robust, compression spring situated over the clutch shaft between the two main bearings in all bicycle engines. It should not be mistaken for the thin tension/extension clutch spring that is sometimes found atop the clutch cover on older models. This main spring is significantly larger, thicker, and resistant to compression. Due to its central location within the clutch, nearly complete disassembly of the gas bike engine might be necessary for replacement.