Wiseco Top End Kit Wiseco leads the performance aftermarket by producing the highest quality forged pistons for Dirt Bikes, ATV's, Snowmobiles, Outboard Marine and Motorcycles in the. Wiseco is unique because all of the pistons are forged in house. All of the forge tooling is also produced in the USA. All aspects of the manufacturing process is controlled, from the raw bar to skirt coating finished parts. Extreme racing conditions demand the strength and toughness that only forged pistons can offer. Compared to cast pistons, forgings are tougher and more durable, and will stand up to the abuse that high performance motorsport applications require. Most castings are brittle, have no grain structure and tend to fail catastrophically when the material yield strength is exceeded. Forgings have condensed grain that is aligned to the features of the part, which produces higher mechanical properties, and resistance to impact and fatigue. Each forging is designed to optimize the strength-to-weight ratio, and maximize performance. It is designed for the YFM660 Grizzly 2002-2008, YFM660R Raptor 2001-2006, YXR66 Rhino 2004-2007.