http://www.quad-motorrad-ersatzteile.de/quad/yamaha/sport-quad/raptor-660-700/yamaha-yfm-660-r-tuning-nockenwelle-ventilfedern.html

Stage 2: single-cam motor. More top-end than Stage 1. Requires Hot Cams spring kit part number SKYFM660S2. Uses stock auto-decompression mechanism.