77-98 YAMAHA YZ250: Vortex Front Sprocket (13T) For more than 15 years, U.S.-based Vortex Racing continues to manufacture, market and sell top-quality motorcycle racing components for Motocross, Supercross, Road Racing, Flat Track Racing and Minibikes. Owned and operated by motorcycle racers and enthusiasts, they focus on absolute quality. Each of their race components is made to the tightest tolerances with the best quality materials in the industry. Vortex tests on the track with direct feedback from top professional race teams worldwide. Vortex parts have been put to the test by some of the world's most respected champions and teams.