Yamaha - Crankshaft Gear Engine Timing Component YF1-52712-41-10. Overview. When you're inside a Yamaha engine, the crankshaft gear is where everything starts-it drives the timing that keeps the whole motor in sync. I've seen engines with worn gears that just never run quite right, no matter what else you fix. The Yamaha Crankshaft Gear YF1-52712-41-10 is what keeps that rotation precise so the camshaft and valves stay on time. It's one of those core components that doesn't get attention often,