Honda Brand 16620-Z8D-305 Thermo Wax Assembly & 16600-Z8B-900 Choke Control - Fits Honda GCV160 GCV160A0 GCV160LA0 GCV190
Honda GCV160 engine repair kit with thermo wax assembly, choke control, fuel shut-off valve, spark plug, and gaskets.
Dimension diagram showing Honda GCV160 engine parts including thermo wax assembly, spark plug, and small metal component.
Repair kit for Honda GCV160 and GCV190 engines including choke control, thermo wax assembly, fuel valve, plug, and gaskets.
Infographic showing Honda lawn mower engine replacement parts: choke control, fuel shut-off valve, and thermo wax assembly.
Honda GCV160 GCV190 lawn mower thermo wax assembly, choke control, fuel shut-off valve, and gasket kit with model chart.
Honda GCV160 engine repair kit with thermo wax assembly, choke control, fuel shut-off valve, gaskets, and spark plug.
Four-angle view of Honda GCV160 engine thermo wax assembly and choke control component.
Honda GCV160 engine parts kit including thermo wax assembly, choke control, fuel valve, spark plug, and gaskets.
Four-step installation guide for Honda GCV160 lawn mower engine thermo wax and choke control parts.
Mechanic repairing a Honda GCV160 lawn mower engine with thermo wax assembly and choke control parts displayed.
Honda GCV160 engine repair kit with thermo wax assembly, choke control, fuel shut-off valve, spark plug, and gaskets.
Dimension diagram showing Honda GCV160 engine parts including thermo wax assembly, spark plug, and small metal component.
Repair kit for Honda GCV160 and GCV190 engines including choke control, thermo wax assembly, fuel valve, plug, and gaskets.
Infographic showing Honda lawn mower engine replacement parts: choke control, fuel shut-off valve, and thermo wax assembly.
Honda GCV160 GCV190 lawn mower thermo wax assembly, choke control, fuel shut-off valve, and gasket kit with model chart.
Honda GCV160 engine repair kit with thermo wax assembly, choke control, fuel shut-off valve, gaskets, and spark plug.
Four-angle view of Honda GCV160 engine thermo wax assembly and choke control component.
Honda GCV160 engine parts kit including thermo wax assembly, choke control, fuel valve, spark plug, and gaskets.
Four-step installation guide for Honda GCV160 lawn mower engine thermo wax and choke control parts.
Mechanic repairing a Honda GCV160 lawn mower engine with thermo wax assembly and choke control parts displayed.
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16620-Z8D-305 Thermo Wax Assembly & 16600-Z8B-900 Choke Control - Fits Honda GCV160 GCV160A0 GCV160LA0 GCV190

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16620-Z8D-305 Thermo Wax, 16600-Z8B-900 Choke Control, and 16950-Z0Y-003 Fuel Valve Kit

Key Features

  • Complete automatic choke restoration kit designed to regulate engine startup behavior based on operating temperature.
  • Thermo wax assembly utilizes precise thermal expansion properties to actuate the carburetor choke valve automatically without manual user adjustment.
  • Mechanical choke control linkage plate ensures crisp, unhindered movement of the choke butterfly valve.
  • In-line fuel shut-off valve features a fuel-resistant internal seal to completely cut off fuel supply during storage, maintenance, or transportation.
  • Engineered to factory specifications to eliminate hard starting, rough idling, and black exhaust smoke caused by improper air-fuel ratios.

Replaces / Cross-Reference Part Numbers

  • 16620-Z8D-305 - Thermo Wax Assembly: 16620-Z8D-305, 16620-Z8D-841, 16620-Z8D-842, 16620-Z9L-003
  • 16600-Z8B-900 - Choke Control: 16600-Z8B-900
  • 16950-Z0Y-003 - Fuel Shut-Off Valve: 16950-Z0Y-003

Compatibility & Fitment

  • Compatible with Honda four-stroke overhead cam small engines.
  • Fits specific engine models including: GCV160, GCV160A0, GCV160LA0, and GCV190.
  • Fits Honda walk-behind lawn mower models including: HRR216 and HRX217.

When to Replace

  • The lawn mower engine is extremely difficult to start from a cold rest or bogs down immediately after cranking.
  • The choke plate stays permanently closed or open, leading to fuel flooding or an overly lean running condition.
  • The thermo wax actuator cylinder pin is seized, bent, or fails to extend as the engine reaches operating temperature.
  • Fuel continuously drips from the body of the fuel petcock switch or bypasses the valve when turned to the off position.

Installation Tips

  • Disconnect the spark plug wire and allow the engine to cool down completely before handling fuel or mechanical linkages.
  • Clamp the main fuel lines using line-clamping pliers or drain the gasoline tank entirely into an approved container before swapping the fuel shut-off valve.
  • Take a digital photograph of the return spring and choke linkage orientation prior to disassembly to ensure accurate reinstallation alignment.
  • Ensure the thermo wax capsule sits completely flush within its designated mounting bracket slot on the engine assembly to prevent binding.
  • Manually cycle the choke control mechanism after final bolt tightening to verify the linkages move smoothly through their full range of motion.

FAQ

If your engine struggles to start when cold, fails to idle correctly, or exhibits erratic choke behavior, the thermo wax assembly is likely failing. Since this component uses heat to automatically adjust the choke, a faulty unit will often leave the choke partially closed or open, leading to rough running or a failure to start entirely.
This kit is compatible with Honda GCV160, GCV160A0, GCV160LA0, GCV160LA1, GCV190, and GCV190LA engines. It is also commonly used on HRX217 and HRR216 series lawn mowers.
Before removing the old components, take a digital photograph of the return spring and choke linkage orientation. This serves as a vital reference to ensure the new parts are aligned correctly during reassembly. Additionally, ensure the thermo wax capsule sits completely flush within its designated mounting bracket slot.
Replacing these components requires patience and precision. You will need to access the carburetor area, which may require tilting the mower. Be careful when aligning the choke plate and linkage to avoid damaging the gaskets or misaligning the control arm. If you are comfortable with basic engine maintenance, it is a manageable task, but take your time to ensure all linkages move freely without binding.
Since you are already accessing the carburetor area, it is a good time to inspect your carburetor gaskets and the air filter. If the gaskets are brittle or torn, they should be replaced to ensure a proper seal and prevent vacuum leaks that could affect engine performance.