Yamaha YZ400F 98-99/WR400F 98-02 Dirt Bike Vertex Pro-Replica Piston Kit (91.93)

• All pistons are heat treated with a T-5 hardening and tempering cycle; piston skirts are coated with a hi-tech molybdenum disulphite for faster break-in time and increased piston life
• Piston kits include piston, rings, wrist pin and circlips
• Replica piston kits are gravity cast aluminum alloy (not forged) with 18% silicone content, which produces an extremely light but very strong piston
• Pro pistons are forged from 2618 aluminum for superior strength and durability
• Replica Big Bore (Replica-BB) are big bore stock compression cast pistons
• Pro-Replica pistons are forged OEM replacements
• Big Bore pistons increase engine?s displacement, torque, and peak horsepower
• Pro Big Bore (Pro-BB) pistons are a forged OEM stock compression big bore piston
• Pro-Race pistons are unique forged GP-style race pistons with only one compression ring
• Pro-High Compression (Pro-HC) pistons are forged and improve power and torque across entire rpm range
• Replica pistons and all rings are OEM replacements
• Replacement two-stroke piston rings sold individually; four-stroke piston rings sold as a set