Piston Pin Compatible With 1987-1989 Honda Trx-R 250Cc Fourtrax 250R 18Mm Wrist Pin 13111-Ha2-770

Manufacturer Part Number:
04.1850

Cross-Reference OEM Part Numbers:
Honda: 13111-HA2-770

Pin Specifications:
• Outer Diameter: 18mm
• Material: Case-hardened chrome steel

Engine Specifications:
• 249cc SOHC 2-Valve 4-Stroke Single Cylinder — Liquid Cooled
• High-performance sport ATV engine

Notes:
• Piston pin (wrist pin) connects piston to connecting rod small end
• The TRX-R 250 (Fourtrax 250R) was Honda's premier sport/racing ATV
• Replace during top-end rebuild or when pin shows wear
• Always replace circlips when removing pin

Function:
The piston pin (also called a wrist pin or gudgeon pin) is the hardened steel shaft that connects the piston to the connecting rod small end. It transfers combustion force from the piston to the connecting rod while allowing the rod to pivot as the crankshaft rotates. A worn, scored, or loose piston pin causes knocking noise, accelerated bore wear, and potential catastrophic engine failure.

When to Replace:
• During any top-end rebuild (piston, rings, cylinder re-bore/re-plate)
• When pin shows visible wear, scoring, discoloration, or blue heat marks
• When pin has measurable play in the connecting rod small end bearing
• Recommended every 2nd piston replacement even if pin appears serviceable

Installation Notes:
• Always replace piston pin circlips — never reuse old circlips
• Apply assembly oil or premix to pin before installation
• Ensure circlips are fully seated in their grooves — improper seating causes engine damage
• Verify connecting rod small end bearing condition before reassembly
• TRX-R 250 is a high-performance sport ATV — ensure all components are within spec during rebuild

PRODUCT NOTICE:
As a parts distributor we mostly sell aftermarket parts (any OEM parts would be noted as such). Aftermarket parts are not sourced from the original vehicle or equipment manufacturer, but are designed to function the same as - if not better than - the original. All parts sold are new.

WARNING - This product may expose you to chemicals which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov