Restore peak compression and power with the OS 1.50 piston kit designed for Kawasaki KLF220 Bayou engines spanning 1988 through 2003. The OS 1.50 oversize bore (67.50 mm) provides a precise match for rebuilt cylinders, delivering crisper throttle response and dependable performance whether you’re tearing through trails or putting in work on the land. Engineered to meet or exceed OEM standards, this aftermarket replacement brings renewed top-end performance and longer service life under demanding riding conditions.

Beyond simple bore size, this OS oversize kit targets common top-end wear: piston skirt scuffing, ring-land wear, and compression loss that rob power. The forged aluminum piston delivers strength and thermal stability for tough terrain, while the complete kit options (notably the Wiseco PK1048) include all necessary components for a true rebuild, so you can trust long-lasting reliability on the trail or on the job site.

Comprehensive Vehicle Fitment

Sources: Wiseco PK1048 overview (67.50 mm oversize for KLF220 Bayou), Namura NA-20001 standard bore option, and general KLF220 Bayou fitment references.

Product Specifications

OEM & Aftermarket Cross-Reference Information

What's Included

A short-top-end rebuild kit option includes the following components. Piston Kit – Wiseco PK1048 includes: Piston, Rings, Wrist Pin, Circlips, and Top-End Gasket Kit.
Piston Kit – Namura NA-20001 includes: Piston (standard bore).

• Piston (67.50 mm oversize for PK1048)
• Rings
• Wrist Pin
• Circlips
• Top-End Gasket Kit (Wiseco option)

Note: Namura NA-20001 standard bore option typically includes the piston only; other top-end components may not be included.

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility: Precisely engineered to match Kawasaki KLF220 Bayou engines from 1988–2003 for straightforward installation.
• OEM Cross-Reference: Cross-referenced with standard and oversize bore options (66.97 mm and 67.50 mm) to match your rebuild plan.
• Premium Materials: Forged aluminum piston (2618 alloy) delivers higher strength and better thermal stability under load.
• Performance Restoration: Oversize 67.50 mm bore with 9.3:1 compression restores power and throttle response after wear.
• Versatile Bore Options: Choose standard (Namura NA-20101) or oversize (Wiseco PK1048) to suit the cylinder you’ve prepared.
• Durable Top-End Kit: When paired with the PK1048, you get a complete top-end gasket kit and all required components for a reliable rebuild.

Installation Notes:

• Verify bore size before purchase: standard bore (Namura NA-20001) vs oversize (+0.50 mm) bore (Wiseco PK1048) and ensure the cylinder is prepared accordingly (boring/honing as required).
• Clean the cylinder and hone or bore to the correct finish for proper ring seating; inspect the cylinder for wear or scoring before assembly.
• Install piston rings with correct orientation and stagger end gaps to prevent gas blow-by; align gaps away from the intake and exhaust ports.
• Lubricate the piston, rings, and wrist pin with assembly oil during install to protect the finish on first start.
• Attach wrist pin and secure with circlips fully seated; double-check for clearance around the wrist pin bore.
• Install the full top-end gasket kit when using the Wiseco PK1048 kit; ensure mating surfaces are clean and free of oil or debris to seal properly.

Why Upgrade?

Worn piston and top-end components degrade compression, throttle response, and overall power, increasing heat and wear on the cylinder. Upgrading to this OS oversize piston kit restores compression and reliability, delivering consistent performance in rugged trail and farm work while reducing the risk of top-end failures during demanding use.