Piston Kit OS 0.25 For Yamaha YFM 450F Kodiak Grizzly Rhino 2003 2014 OEM Replacement
Piston Kit OS 0.25 For Yamaha YFM 450F Kodiak Grizzly Rhino 2003 2014 OEM Replacement is backordered and will ship as soon as it is back in stock.
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Piston Kit OS 0.25 For Yamaha YFM 450F Kodiak Grizzly Rhino 2003 20...
OS 0.25 oversize piston kit designed to rebuild the top end of 450cc four-stroke ATV engines. It restores compression and power across the mid-2000s to mid-2010s models, delivering reliable performance on trail chores and workdays. The.25 mm oversize compensates bore wear, helping to maintain a clean ring seal and smooth throttle response. Packaged as a complete top-end rebuild kit, it includes all necessary components for a straightforward installation.
Forged aluminum OS piston delivers proven strength and heat tolerance under harsh riding conditions, making this kit a dependable upgrade for a fleet or single rider alike. The kit includes the piston, rings, wrist pin, and circlips to provide a ready-to-install top-end package. Its broad compatibility across a 450cc-class ATV engine family means you can refresh multiple machines with one rebuild strategy, simplifying maintenance on a rural trail or farm fleet.
Comprehensive Vehicle Fitment
| Manufacturer | Models / Series | Years / Details |
|---|---|---|
| Yamaha | YFM450 Kodiak | 2003–2014 |
| Yamaha | YFM450 Grizzly | 2007–2014 |
| Yamaha | YXR450 Rhino | 2006–2010 |
| Yamaha | YMF450 Wolverine | 2006–2010 |
Product Specifications
| Attribute | Details |
|---|---|
| OEM Reference Part Numbers | Varies by bore size and supplier; verify exact numbers on kit packaging or with your dealer. |
| Type | Piston Kit (4-stroke) |
| Manufacturer | Aftermarket Replacement |
| Application | YFM450 Kodiak, Grizzly, Wolverine, Rhino top-end rebuilds |
| Material | Forged aluminum alloy (commonly 2618) |
| Piston Size / Oversize | OS 0.25 (0.25 mm oversize) |
| Inclusions | Piston, Rings, Wrist Pin, Circlips |
| Coating / Finish | Skirt coating options (e.g., ArmorGlide in the aftermarket segment) |
OEM & Aftermarket Cross-Reference Information
| Part Number | Brand / Type | Cross-Reference Notes |
|---|---|---|
| NA-40011-4 | Namura Piston Kit | Oversize +0.25 to +0.50 options exist; compatible with multiple 450cc Yamaha models; verify bore size on packaging. |
| 8904DA | Wossner Piston Kit | YFM450 Kodiak/Grizzly/Wolverine/Rhino applications; oversize options +0.50 and +1.00 available; includes rings, wrist pin, and circlips. |
| 4939M08450 | Wiseco Piston Kit | 85.00 mm bore option (+0.50); includes piston, rings, wrist pin, and circlips; common cross-reference for 450cc Yamaha models. |
| NA-40011-2 | Namura Piston Kit | Standard to overweight fitment notes vary by model; consult catalog for exact match. |
What’s Included
This OS 0.25 piston kit ships with the essential components needed for a complete top-end rebuild.
- Piston
- Rings
- Wrist Pin
- Circlips
Gaskets, seals, and timing components used in the full engine overhaul are not included; replace them as part of a complete top-end refresh.
Why Choose This Aftermarket Replacement?
- Direct-Fit Compatibility: Precision oversize kit designed to restore OEM compression without modifying the cylinder or carriage.
- OEM Cross-Reference: Backed by multiple aftermarket brands that cover the same 450cc Yamaha platforms for flexible sourcing.
- Forged Aluminum Construction: Strong, heat-tolerant 2618-grade aluminum forged piston for long life under harsh conditions.
- Complete Top-End Rebuild Kit: Includes piston, rings, wrist pin, and circlips for a turnkey installation.
- Premium Finishes & Coatings: Skirt coatings and forged design help reduce scuffing and wear during break-in and everyday use.
- Performance Restoration: Restores original compression, power, and throttle response after bore wear.
Installation Notes:
- Verify bore size and confirm OS 0.25 suitability before ordering or installation.
- Use proper assembly lubrication on rings and wrist pin; avoid dry-fitting components.
- Follow the torque specifications from the service manual for wrist pins and any fasteners involved in the top-end assembly.
- Inspect the cylinder bore for wear; if scoring or glazing is present, consider honing or re-boring per factory guidelines.
- Replace gaskets, seals, and the head gasket as part of a full top-end rebuild to ensure a reliable seal.
- Run a proper break-in procedure after installation to seat rings evenly and prevent scuffing.
Why Upgrade?
A worn piston and bore seal can rob compression, reduce power, and increase heat transfer as rings lose contact with the cylinder wall. Upgrading to this OS 0.25 piston kit restores compression, improves ring seal, and brings back the smooth power delivery you expect from a fresh top end, even after heavy trail or farm use. This rebuild restores reliability and helps prevent further engine scoring or heat-related wear by renewing the critical top-end components.
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