Yamaha - Gear, ring - 67F-81891-00-00Yamaha Gear, Ring Starter System Component 67F 81891 00 00 Overview When a Yamaha has trouble engaging during startup, the ring gear is one of those parts that cant be overlooked. Its what the starter gear grabs onto to turn the engine over, so if its worn or damaged, youll hear grinding or slipping right away. Ive seen engines struggle to crank just because the teeth on this gear were worn down. When its in good condition, the starter engages clean