Yamaha Genuine OEM Standard Size 2-Stroke Piston (66.4mm) | 1P8-11631-00
$115.00
Sale price
$115.00
Regular price
$179.99
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Yamaha Genuine OEM Standard Size 2-Stroke Piston (66.4mm) | 1P8-11631-00
$115.00
Sale price
$115.00
Regular price
$179.99
Restore the compression, power, and factory throttle response of your machine with this Genuine Yamaha OEM Standard Size (STD) Piston (1P8-11631-00). Engineered specifically for Yamaha’s legendary 2-stroke 250cc powerhouses, this factory-original piston is manufactured from premium-grade alloys to perfectly balance lightweight performance with extreme thermal durability.
Unlike generic options, choosing a genuine Yamaha part guarantees a precise skirt profile, ideal ring-groove geometry, and the exact wrist-pin bore alignment required to prevent critical top-end binding or premature skirt collapse under heavy load. Keep your engine running reliably on the track or the trail with the same exact part it came with from the factory floors of Japan.
Note: This listing is for the bare standard piston only. For a comprehensive top-end rebuild, we recommend purchasing a fresh wrist pin, circlips, and a matching ring set.
Key Product Features & Benefits
- Factory-Specified Fitment: Ensures optimal piston-to-cylinder clearance for minimal blow-by and enhanced performance longevity.
- Premium Alloy Cast: Engineered to handle the high heat and explosive RPM ranges inherent to high-performance 2-stroke engines.
- Exact Weight Balancing: Engineered directly to original factory weight specifications to minimize crank vibration and bearing stress.
- Direct OEM Safety: Avoid the inconsistent tolerances of generic imports with a 100% genuine Japanese replacement part.
📋 Technical Specifications
- Manufacturer: Yamaha
- Base Part Number: 1P8-11631-00 (Common sub-variants include: -00-A0, -00-B0, -00-C0, -00-D0)
- Component Type: Engine Hard Part / Internal Piston
- Cylinder Bore Size (OEM): 66.40 mm (Standard Size / Size A/B/C/D)
- Engine Type: 2-Stroke
- Country of Manufacture: Japan
🏍️ Exact Vehicle Fitment
This OEM part is engineered specifically for the following models:
| Year | Make | Model | Sub-Model / Fitment Group |
|---|---|---|---|
| 2005 – 2027 | Yamaha | YZ250 | 2-Stroke Motocross Base & 50th Anniversary Models |
| 2016 – 2027 | Yamaha | YZ250X | 2-Stroke Cross-Country GNCC / Off-Road |
(Fits older 1999–2004 YZ250 applications where parts group updates cross-reference seamlessly to 5NX-11631-00-A0).
🔄 Cross-Reference & Part Numbers
- OEM FActory Sub-Skus: 1P8-11631-00-A0, 1P8-11631-00-B0, 1P8-11631-00-C0, 1P8-11631-00-D0 (Yamaha designates trailing letter codes for minuscule, factory-graded micrometer matching steps A, B, C, or D).
- Superseded Yamaha Part: 5NX-11631-00-A0
- ProX Racing Equivalent: ProX 01.2321.B (Standard 66.36mm - 66.40mm Bore)
- Vertex Racing Equivalent: Vertex 22591D / Replica Series
- Wiseco Performance Equivalent: Wiseco 803M06640 (Pro-Lite Series)