This Standard Bore Piston Kit with a 78.5 mm bore is designed for top-end rebuilds on the TRX350 Rancher family from 2000 through 2006. It restores compression and power, helping maintain reliable performance on trail work or demanding farming duties. Engineered to meet factory-like tolerances, this aftermarket kit provides a proven, cost-effective solution for renewing your engine’s heartbeat without guessing at compatibility.

With a complete set that includes the piston, rings, wrist pin, and circlips, this replacement kit tackles common wear such as bore wear and ring-seal degradation that steal throttle response and efficiency. Built as a reliable aftermarket option for trail or farm use, it combines a precise bore size with durable materials to keep your Rancher running strong through demanding jobs and long days in the field.

Comprehensive Vehicle Fitment

Fitment confirmed for the TRX350 Rancher variants produced between 2000 and 2006, including 2x4 and 4x4 configurations.

Product Specifications

Standard bore and material details align with common TRX350 rebuild requirements, with bore verified at 78.50 mm and 68.00 mm stroke.

OEM & Aftermarket Cross-Reference Information

Cross-reference data reflects aftermarket equivalents such as Wossner 8871DA and Wiseco 4933M07850 for the 78.50 mm standard bore TRX350 kits.

What's Included

This kit includes the essential components needed for a straightforward top-end installation:

• Piston
• Rings
• Wrist Pin
• Cir Clips

Note: Related parts such as gaskets, seals, and gasket kits are not included and should be sourced separately.

Why Choose This Aftermarket Replacement?

• Direct-Fit Compatibility — precise 78.50 mm standard bore matches the TRX350 Rancher’s factory specification for reliable top-end upgrades.
• OEM Cross-Reference Availability — clear cross-references to the factory numbers help you verify compatibility with familiar engine parts and service manuals.
• Premium Materials — aluminum alloy piston with a moly-coated skirt (as used by leading aftermarket brands) reduces friction and enhances durability in dusty, hot farm conditions.
• Performance Restoration — restores lost compression and throttle response, delivering predictable power for trails and work tasks.
• Complete Top-End Kit — includes piston, rings, wrist pin, and circlips, simplifying installation and reducing the risk of missing components.
• Aftermarket Replacement Quality — designed to meet or exceed factory tolerances, offering a cost-effective rebuild without OEM pricing.

Installation Notes:

• Cleanliness is critical — thoroughly clean the bore and transfer surfaces; any debris can score the cylinder walls and ruin a new ring seal.
• Ring gaps and orientation — verify end gaps and install the rings in the correct orientation to prevent blow-by and scuffing.
• Lubrication — apply a light film of engine oil to the piston, rings, and wrist pin before final assembly to reduce startup wear.
• Ring compressor and alignment — use a proper ring compressor to avoid ring damage and ensure even seating of the piston in the bore.
• Wrist pin and circlips — seat both circlips fully and confirm the wrist pin is secure from side-to-side movement before reassembly.
• Follow service manual torque guidance — use the OEM service manual for head, splash, and crankcase fasteners to avoid over- or under-tightening during reassembly.

Why Upgrade?

Running a worn piston kit can progressively reduce compression, increase oil consumption, and invite scoring or overheating under load. This replacement restores factory-like bore integrity and reliable power, delivering trustworthy performance for daily riding, work, and long days in the field.