Wiseco High-Performance Forged Piston Kit (+1.00mm Oversize / 84.00mm) 40123M08400

Wiseco High-Performance Forged Piston Kit (+1.00mm Oversize / 84.00mm)

Part Number: 40123M08400 | Compression Ratio: 12.0:1 | Displacement: 357cc

Product Overview

Restore compression and boost output in your Yamaha 350 engine with this Wiseco Forged Piston Kit. Engineered, forged, and CNC-machined in the USA using high-silicon 2618 aerospace aluminum alloy, Wiseco forged pistons offer significantly higher impact resistance, fatigue strength, and heat dissipation than standard cast pistons.

Note: This is a 1.00mm oversize piston kit (84.00mm bore) and requires cylinder reboring/honing prior to installation.

Key Features

• Complete Top-End Kit: Includes high-performance 84.00mm piston ring set (3307XC), 19mm wrist pin (S376), and round wire pin locks/circlips (CW19).

• ArmorGlide Skirt Coating: Features Wiseco’s friction-reducing skirt coating for lower operating temps and smooth, quiet break-in.

• Forged Strength: High-density grain structure handles extreme heat and RPM without risk of brittle casting failure.

• Optimized Compression: 12:1 high-compression dome design provides immediate throttle response and added torque.

Vehicle Fitment

Fits the following 350cc Yamaha ATV / Quad models (requires cylinder bored to 84.00mm):

• Yamaha YFM350X Warrior: 1987 – 2004

• Yamaha YFM350 Raptor: 2004 – 2013

• Yamaha YFM350 Grizzly (2WD / 4WD / IRS): 2007 – 2014

• Yamaha YFM350 Wolverine (2WD / 4WD): 1995 – 2009

• Yamaha YFM350FW / YFM350U Big Bear: 1987 – 1999

• Yamaha YFM350ER Moto-4: 1987 – 1995

Specifications

• Brand: Wiseco Performance Products

• Part Number: 40123M08400

• Engine Type: 4-Stroke

• Standard Cylinder Bore: 83.00 mm

• Actual Cylinder Bore: 84.00 mm

• Actual Piston Diameter: 83.95 mm

• Bore Oversize: +1.00 mm (+0.040 in)

• Stroke: 64.50 mm

• Compression Ratio: 12.0:1

• Country of Origin: Made in the USA

• Condition: Brand New in Original Packaging