This 4-5/8" stroke 8-1/2" diameter flywheel assembly fits 2007-'16 internally balanced HD® big twin models as part of an S&S® 124" Hot Set Up Kit®. Sprocket shaft does not have a stock style bearing race pressed on. This flywheel assembly is for crankcases with Timken® sprocket shaft bearing. Pinion shaft has sprocket to drive balancer chain.