Description
Overview:
This Genuine JAP piston assembly is designed for the JAP 2A and 2S petrol engines found in older construction, agricultural and garden machinery. Made from durable cast aluminium alloy for strength, low weight and good heat transfer, it restores correct combustion efficiency when used with a rebored cylinder. The oversize is +0.020 inch (+0.51 mm), allowing you to take up wear after a rebore and regain compression. Supplied as OEM No. SA3137/020, it offers factory-correct dimensions for reliable fitment in compatible engines. As an unused old-stock vintage part, it may show minor storage-related marks or tarnishing that do not affect function. Ideal for engine rebuilds, maintenance and authentic restorations where original JAP specification and performance are required.
Key Features:
- Genuine JAP OEM component for accurate fit and performance (OEM No. SA3137/020)
- Oversize +0.020 inch (+0.51 mm) to suit rebored cylinders and recover compression
- Cast aluminium alloy construction for strength and efficient heat dissipation
- Precision-machined crown, skirt and ring lands for consistent sealing and smooth running
- Suitable for vintage engine rebuilds where authenticity and reliability matter
- Helps reduce oil consumption and blow-by when paired with a correct bore finish
- Compatible with JAP 2A and 2S stationary engines commonly used in small plant and machinery
- Practical choice for restorers and workshops maintaining heritage equipment
- Unused old-stock item; cosmetic signs of age may be present but performance remains as intended
- Best fitted with careful measurement of bore size, clearances and ring gaps
Typical Applications:
Engine rebuilds and refurbishments of JAP 2A/2S units powering classic cement mixers, generators, water pumps, compactors, mowers and small agricultural equipment. Useful for heritage machinery restorations, museum exhibits, and keeping older plant in service where parts must match original specifications and dimensions.
Also known as:
+0.020 inch oversize piston (+0.51 mm), 20‐thou oversize piston, oversize rebore piston, piston for JAP stationary engine, JAP 2A piston, JAP 2S piston, SA3137/020 piston assembly, vintage JAP piston, OS 020 piston.
Fits Models:
JAP 2A
JAP 2S
Product Specifications
| L&S Part No. | SA3137/020 |
|---|---|
| Part Type | Genuine Part |
| Manufacturer | JAP |
| OEM No. | SA3137/020 |
| Unit of Sale | 1 |
| Key Features | - Genuine JAP OEM component for JAP 2A and 2S engines - Oversize +0.020 inch for rebored cylinders - Cast aluminium alloy for strength and heat dissipation - Precision-machined for consistent sealing and smooth running - Suitable for vintage engine rebuilds and restorations |
| Fits Models | JAP 2 |
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