Wiseco 4312M07100 Forged Piston Kit Oversize - 71mm 1.00mm YTM/YFM225

The Wiseco 4312M07100 is a forged aluminum piston kit designed as a +1.00mm (0.040") oversize replacement for Yamaha YTM and YFM 225cc ATVs. Machined to a finished bore diameter of 71.00mm from a standard 70.00mm bore, this kit is ideal for engines that have been bored out during a rebuild. Each kit includes the piston, rings, circlips, and wrist pin.

Key Specifications:

• Bore Size: 71.00mm (1.00mm / +0.040" oversize)
• Standard Bore: 70.00mm
• Stroke: 58.00mm
• Displacement: 226cc
• Compression Ratio: 10.25:1
• Material: Forged high-silicon aluminum alloy

Key Features:

• Forged Construction: Wiseco pistons are forged from high-silicon, low-expansion aluminum, offering superior strength, reduced weight, improved heat transfer, and extended service life compared to cast alternatives.
• Precision CNC Machining: Diamond-turned on CNC turning centers for a consistent finish with zero size variation, ensuring proper fit and seal in any cylinder bore composition — including cast iron, chrome, Nikasil, and boron composite.
• Oversize Rebuild Solution: This +1.00mm oversize piston is engineered to restore proper clearances after cylinder boring. Compatible with resleeved cast iron cylinders as well as chrome, Nikasil, and boron composite cylinders.
• Application-Specific Design: Engineered using 3D design techniques and finite element modeling to deliver the optimal combination of strength and reduced reciprocating weight for this specific engine.

Each kit includes the piston, piston rings, circlips, and wrist pin — everything needed to complete a top-end rebuild. Note: cylinder boring is required for installation of this oversize piston.