The Honda 13103-ZG8-000 Piston (0.50) is a genuine OEM oversize piston designed for GX640 horizontal shaft engines, H4518 lawn tractors, and H5518 multi-purpose tractors. As a 0.50 mm oversize component, this piston is intended for engines whose cylinder bore has been machined or honed to accept an oversized piston — verify your bore size before ordering to confirm this is the correct oversize for your rebuild. Sourced directly from Honda, it carries the exact dimensions and tolerances Honda specifies for a proper rebuild on these machines.
Key Features
- Genuine OEM Oversize Piston — manufactured by Honda to the exact profile and crown geometry required for the 0.50 mm oversize bore specification on these engines and tractors
- Bore-Size Verification Required — the (0.50) designation identifies this as an oversize piston; confirm your machined cylinder bore matches this oversize before installation
- Broad Fitment — covers GX640 horizontal shaft engines, H4518 lawn tractors, and H5518 multi-purpose tractors; check your serial number against the fitment table to confirm applicability for your unit
- Restored Compression and Power — a correctly sized OEM piston re-establishes the proper bore-to-piston clearance, restoring compression, combustion efficiency, and oil control that a worn standard-bore piston can no longer maintain
The piston is the reciprocating heart of a four-stroke engine, moving up and down inside the cylinder bore to compress the air-fuel mixture and transfer combustion force to the crankshaft via the connecting rod. When a cylinder bore wears beyond standard limits, it is bored out to a precise oversize dimension and fitted with a matching oversize piston — in this case the 0.50 mm oversize — to restore the tight clearance needed for proper compression and controlled oil consumption. Running an engine with a worn piston-to-bore fit results in blow-by, loss of power, excessive oil use, and accelerated wear throughout the top end.
Part Details
| Part Number | 13103-ZG8-000 |
|---|---|
| Brand | Honda |
| Part Type | Genuine OEM |
| Description | Piston (0.50) |
Compatibility & Fitment
| Name | Models | Serial Range |
|---|---|---|
| Horizontal Shaft Engine | GX640 | All |
| Lawn Tractor | H4518 | All |
| Multi-Purpose Tractor | H5518 | All |
Verify Before You Order
Fitment is machine-number and revision-specific; always confirm your model and serial number against the fitment list.
Why Buy From DHS Equipment
Every part is verified against the manufacturer's part number before it ships, so what you order is what arrives. We carry parts from leading OEM brands and our own DHS Quality Parts line of professional aftermarket components. Need help finding the right part? Our team is available to confirm compatibility whenever you need it. Orders are processed fast to keep your jobs on track. We don't just sell parts. We keep you jobsite ready.
Questions? Contact our team at [email protected] or 866-611-9369 — DHS Equipment is here to help you maintain peak performance.
