Namura .040 Over Bore Piston Kit for Polaris Sportsman 400 450 Ranger 425 88.9mm

.040 Over Bore Piston Kit for Polaris Sportsman 400 450 Ranger 425

This .040 over bore piston kit for Polaris Sportsman 400, 450, and Ranger 425 provides an oversized piston (88.9mm) for engines bored to the first oversize.

Overview

This .040 over bore piston kit for Polaris Sportsman 400, 450, and Ranger 425 includes a piston, rings, and wrist pin for a complete engine rebuild. The 88.9mm piston is designed for cylinders that have been bored .040 inches over standard. Use this piston kit to restore compression and performance in your Polaris ATV or utility vehicle.

Built For Performance

• Constructed from high-silicone aluminum alloy for lightweight strength
• Oversized .040 (1mm) over standard bore to match oversize cylinders
• Includes durable chrome-plated piston rings for long wear
• Precision-machined for tight tolerances and consistent fit
• Includes wrist pin and circlips for a complete installation

Fits These Machines

• for Polaris Sportsman 400
• for Polaris Sportsman 450
• for Polaris Ranger 425

On-The-Job Use

• Rebuilding engines after bore and hone operations
• Restoring power in high-hour ATVs and utility vehicles
• Custom performance builds and top-end overhauls
• Trail riding and heavy-duty farm work

Specs At A Glance

Good To Know

Q: Can this piston kit be used on a standard bore cylinder? A: No, this .040 over bore kit is designed for cylinders that have been bored oversize; using it on a standard bore will not fit correctly.

Q: Are the rings pre-gapped? A: Rings are not pre-gapped and should be fit to your specific cylinder clearance for optimal performance.

Slight variation in finish or dimensions may occur between production runs, and fit can depend on serial number, so confirm compatibility before ordering.