The Honda 99101-ZH8-1220 Main Jet (#122) is a genuine OEM carburetor component designed for GX630, GX660, GX690, GXV630, GXV660, and GXV690 engines. As an authentic Honda part, it carries the exact orifice sizing your engine's fuel system requires — the #122 designation identifies this specific calibration, and using the correct jet number is essential for proper fuel metering. This part is a direct OEM replacement sourced from Honda, giving you confidence that it matches the original specification for these large-displacement horizontal and vertical shaft engines.
Key Features
- Correct Orifice Calibration — the #122 sizing is factory-determined for precise fuel metering in the GX630, GX660, GX690, GXV630, GXV660, and GXV690 carburetor; substituting the wrong jet number throws off the air-fuel mixture and degrades performance
- Genuine Honda OEM Part — sourced directly from Honda, this component meets the original design specification and integrates with the existing carburetor assembly without alteration
- Broad Large-Displacement Fitment — listed for Honda's 630–690 cc horizontal and vertical shaft engine families; confirm your engine model and serial number against the fitment table before ordering, as Honda supersedes parts at serial breaks
- Fuel System Performance — a correctly sized main jet keeps the engine running cleanly at full throttle; a worn, clogged, or incorrectly sized jet causes rich or lean running, poor power output, and excessive fuel consumption
The main jet is a precisely drilled metering orifice located inside the carburetor body. It controls the volume of fuel drawn into the air stream during mid-to-full throttle operation by allowing a calibrated amount of fuel to pass from the float bowl into the venturi. The number stamped on the jet — in this case #122 — corresponds directly to the orifice diameter, and even a one-step variation in jet size will noticeably affect mixture strength. When a main jet becomes clogged with deposits or damaged, the engine typically exhibits hesitation, loss of power, or rough running under load.
Part Details
| Part Number | 99101-ZH8-1220 |
|---|---|
| Brand | Honda |
| Part Type | Genuine OEM |
| Description | Main Jet (#122) |
Compatibility & Fitment
| Name | Models | Serial Range |
|---|---|---|
| Horizontal Shaft Engine | GX630, GX660, GX690 | All |
| Vertical Shaft Engine | GXV630, GXV660, GXV690 | 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.
