Piston Kit OS 0.50 Honda TRX 420 2007 Through 2023
Piston Kit OS 0.50 Honda TRX 420 2007 Through 2023 is backordered and will ship as soon as it is back in stock.
Delivery and Shipping info
Delivery and Shipping info
- Standard delivery (2-4 working days) - £4.99 on eligible UK mainland orders under £50.
- Express delivery - £6.99 on eligible UK mainland orders placed before 2pm.
- Large equipment including international orders are subject to different delivery rates and timescales.
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Piston Kit OS 0.50 Honda TRX 420 2007 Through 2023 is backordered and will ship as soon as it is back in stock.
This OS oversize piston kit (+0.50 mm) is built for the Honda TRX 420 Rancher family (2007 - 2023) to restore lost compression and bring back strong top-end power with solid mid-range torque. Engineered as an aftermarket replacement, it delivers reliable, consistent power for trail miles and demanding work-site use, without jumping to a larger bore kit. By refreshing the bore with a precise +0.50 mm oversize, this kit helps maintain a durable seal and smooth operation across the TRX 420 lineup.
Designed for riders who push their Rancher hard, this kit focuses on reclaiming throttle response and daily reliability after top-end wear. It’s a practical rebuild solution that preserves factory geometry and keeps the engine performing consistently under load - whether you’re tackling rugged trails, forestry work, or farm duties. The result is a dependable restoration that avoids the jump to a larger bore while delivering noticeable power and torque gains.
OEM & Aftermarket Cross-Reference Information
| Part Number | Brand / Type | Cross-Reference Notes |
|---|---|---|
| 13103-HP5-600 | Honda OEM Piston Kit | OEM reference for TRX 420; aftermarket OS kit serves as a direct replacement with +0.50 mm oversize. |
| 40050M08700 | Wiseco Piston Kit (ArmorGlide) | 87.00 mm bore (+0.50 mm oversize) for Honda TRX 420 Rancher (07 - 15). Common aftermarket cross-reference for +0.50 oversize builds. |
| 50-231-09K | WSM Piston Kit | Examples show +1.5 mm oversize variants for TRX 420; included here as a cross-reference note for context (not the exact oversize in this kit). |
What’s Included
This OS oversize piston kit arrives with the essential components needed to rebuild the top end and restore performance.
- Piston with +0.50 mm oversize bore
- Piston Ring Set matching the oversize piston
- Piston Pin / Wrist Pin and Circlips
- Install Lubricant (small quantity for initial startup, if included by manufacturer)
Note: Gaskets, head cover seals, and other related seals/gaskets are not included and may require separate gasket sets depending on your rebuild scope.
Fitment
| Manufacturer | Models / Series | Years / Details |
|---|---|---|
| Honda | TRX420FA1 Rancher 4x4 Auto | 2014 - 2024 |
| Honda | TRX420FA2 Rancher 4x4 Auto EPS | 2014 - 2024 |
| Honda | TRX420FA5/FA6 Rancher 4x4 Auto IRS | 2015 - 2024 |
| Honda | TRX420FE1 Rancher 4x4 ES | 2014 - 2024 |
| Honda | TRX420FM1 Rancher 4x4 | 2014 - 2024 |
| Honda | TRX420FM2 Rancher 4x4 EPS | 2014 - 2024 |
| Honda | TRX420TE1 Rancher 2x4 ES | 2014 - 2024 |
| Honda | TRX420TM1 Rancher 2x4 | 2014 - 2024 |
Specifications
| Attribute | Details |
|---|---|
| OEM Reference Part Numbers | 13103-HP5-600 |
| Type | Piston Kit OS Oversize +0.50 |
| Manufacturer | Aftermarket Replacement |
| Application | Honda TRX 420 Rancher models (2007 - 2023) |
| Material | Forged aluminum piston (typical industry construction for oversize kits) |
| Bore Size | 87.0 mm (oversize +0.50 mm) |
| Standard Bore | 86.5 mm |
| Stroke | 71.5 mm |
| Displacement | 425 cc |
| Piston Ring Set | Included (top and second compression rings + oil ring) |
| Piston Pin / Circlips | Included (wrist pin and retaining clips typical of kits) |
Installation Notes
- Inspect the cylinder bore for scoring or damage; hone as required before installing the oversize piston.
- Lubricate the wrist pin and rings with assembly lube prior to installation to reduce initial dry startup wear.
- Install the piston rings with the gaps offset as per standard practice to minimize blow-by and oil fouling.
- Use new circlips and ensure they seat fully in the piston grooves to prevent wrist pin movement.
- Verify ring end gaps are within the manufacturer’s specified range after installation and before startup.
- Follow torque and assembly specifications for surrounding components during reassembly and perform a proper break-in procedure.
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