Wiseco 4650M09400 Piston Kit Yamaha Compression - 94mm YZ/WR400 13.5 1 3701XR

The Wiseco 4650M09400 is a high-performance forged piston kit designed for Yamaha YZ400 and WR400 engines. Running a 13.5:1 compression ratio, this piston is engineered for riders seeking maximum power output from their four-stroke powerplant. The kit references Wiseco forging 3701XR and fits a 94.00mm bore diameter.

Key Features:

• Forged from high-silicon aluminum alloy for superior strength, durability, and heat resistance
• 13.5:1 high-compression ratio for increased horsepower and torque
• Innovative forging geometry and optimized piston skirt profile for maximum performance
• CNC-machined to precise tolerances for proper fit and long service life
• Complete kit includes piston, rings, wrist pin, and circlips

Important Notes:

• This is an oversize piston — cylinder boring or sleeving is required for proper installation
• Always verify bore size and measure your cylinder before ordering

Wiseco has been manufacturing forged pistons for motorsports applications for decades and is a trusted name in motocross, off-road, and high-performance engine rebuilding. The 4650M09400 piston kit delivers the reliability and performance demanded by competitive and recreational riders alike.