The Honda 12210-Z4H-405 Cylinder Head (Thai Leakless) is a genuine OEM replacement designed for GX120 horizontal shaft engines and the WB20, WB30, WH15, and WH20 water pumps. As a direct Honda OEM component, this cylinder head is manufactured to the same specification as the part that left the factory, ensuring a proper fit without rework or modification. Confirm your model and serial number against the fitment table before ordering — Honda supersedes cylinder head variants at production breaks, and this leakless designation identifies a specific head design buyers should match to their unit.
Key Features
- Genuine Honda OEM Construction — sourced directly from Honda, this cylinder head meets the same combustion chamber geometry and valve-seat dimensions as the original, ensuring correct compression and thermal management for the engine.
- Leakless Design Variant — the (Thai Leakless) designation identifies this as a specific production variant; verify this matches your unit's existing head spec before installation.
- Broad Fitment — covers GX120 horizontal shaft engines as well as WB20, WB30, WH15, and WH20 water pumps, including models that share this engine platform.
- Check Your Serial Number — Honda introduces revised cylinder heads at defined production breaks; cross-reference your machine's serial number with the compatibility table to confirm part number 12210-Z4H-405 is correct for your serial range.
The cylinder head is the upper casting that seals the top of the engine's combustion chamber, housing the valves, valve seats, and combustion recess. It works together with the head gasket and block to contain the pressure generated during combustion and transfer heat away from the combustion event. A cracked, warped, or otherwise compromised cylinder head allows combustion gases to escape, leading to a loss of compression, overheating, and eventual engine failure — making accurate part identification and proper torque during installation critical to a lasting repair.
Part Details
| Part Number | 12210-Z4H-405 |
|---|---|
| Brand | Honda |
| Part Type | Genuine OEM |
| Description | Cylinder Head (Thai Leakless) |
Compatibility & Fitment
| Name | Models | Serial Range |
|---|---|---|
| Horizontal Shaft Engine | GX120 | All |
| Water Pump | WB20, WB30, WH15, WH20 | 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.
