Wiseco 40109M08300 Forged Piston Kit Compression - 83mm 11 1

The Wiseco 40109M08300 is a high-performance forged piston kit engineered for Yamaha YFM350 ATV engines. Featuring an 83.00mm standard bore diameter and an aggressive 11:1 compression ratio, this kit is built to deliver measurable gains in horsepower and torque over stock components.

Wiseco pistons are forged from high-silicon, low-expansion aluminum alloy, offering superior strength, reduced weight, improved heat transfer, and longer service life compared to cast alternatives. The dedicated forging design and optimized piston skirt geometry are engineered to maximize combustion efficiency and output.

Piston Specifications:

• Bore: 83.00mm (Standard)
• Compression Ratio: 11:1
• Stroke: 64.50mm
• Displacement: 349cc
• Cylinders: 1
• Skirt Coating: ArmorGlide® — reduces operating friction and minimizes skirt and cylinder wall wear
• Wrist Pin: 19mm x 2.500 in. (Part No. S376)

Kit Contents:

• Forged piston
• Ring set — 83.00mm (Part No. 3268XC)
• Wrist pin — 19mm x 2.500 in. (Part No. S376)
• Round wire pin locks — 19mm, pair (Part No. CW19)

Additional Notes:

• Engineered, forged, and machined in the USA
• Oversize pistons require cylinder re-sleeving
• ArmorGlide® skirt coating is applied to the piston skirt for reduced friction and extended engine life