Page 169 of Kawasaki Motorcycles by Kawasaki USA

Kick-starting a large-displacement 4-stroke engine can be a lot of work, we wanted to make sure that the engine would start on the first try, so we incorporated the best automatic compression release (ACR) system available. The dual-weight centrifugal decompression system fitted to exhaust cam eases starting. At cranking speeds, a tension spring holds the flyweights closed causing the ACR pin to extend, holding one of the exhaust valves open slightly. This reduces compression for easier starting. Once the engine is running, the flyweights open. This rotates the ACR shaft which causes the ACR pin to retract allowing normal valve operation. ACR Pin Extended ACR Pin Retracted ACR flyweights open once the engine is running ACR flyweights are closed at cranking speeds

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