2012 YAMAHA PW50 PW50B1, Kid-Friendly. Yamaha Approved. With a seat height of just 19.1 inches, adjustable throttle and fully automatic transmission, the PW50 ensures your kid's first ride is as rewarding as his first step. Key Features Fully automatic transmission means no shifting required the PW50 is a total twist-and-go package. Torque-tuned, spunky little 49cc two-stroke is built to thrill without intimidating beginners. A seat only 19.1 inches high makes this one the logical choice for the littlest rider in the group. An adjustable throttle stop screw lets the adult in charge gradually increase speed as skills improve. Shaft final drive makes chain maintenance a thing of the past.