Boyesen 625 Power Reed For: Yamaha CR500 1984-1988 Power reeds use a patented dual stage fiberglass design for more air flow, more air velocity and more power The top reed is lightweight and resilient for crisp throttle response at partial throttle or low RPMs; the stiffer, bottom reed is ported to provide maximum flow and horsepower at higher RPMs Longer overall life: Boyesen power reeds outlast all other aftermarket reed petals Minor change gives major horsepower improvements and fuel economy