The Multiquip 21387 is a genuine OEM Engine, 4 HP Honda GX120K1QX2 designed for PSH Protoscreed units and C and CA Series walk-behind power trowels including the CA4HC, CA5BC, CA4HM, CA4HM, and CA-4-4H international models. As a direct OEM replacement sourced through Multiquip's authorized parts supply, part 21387 is the correct engine assembly specified for these machines — no guesswork on compatibility. DHS Equipment stocks this part to keep your screed or trowel back in service with the exact power unit the equipment was built around.
Key Features
- Genuine OEM Honda Powerplant — The GX120K1QX2 is the factory-specified 4 HP engine, ensuring correct output, shaft dimensions, and mounting configuration for a drop-in exchange.
- Broad CA and PSH Series Coverage — Confirmed fitment across PSH Protoscreed, CA4HC, CA5BC, CA4HM, and CA-4-4H walk-behind power trowel models, covering a wide range of Multiquip and Whiteman equipment.
- Complete Engine Assembly — Supplied as a full engine unit, so blade engagement, rpm output, and operational characteristics are restored to original spec from the moment of installation.
- Honda GX Series Durability — The GX120K1 is a commercial-grade overhead-cam engine known for consistent power delivery and long service intervals, well suited to the continuous-duty demands of trowel and screed work.
- Verified Multiquip Part Number — Ordering by part number 21387 confirms you are receiving the correct engine variant — critical when multiple GX120 configurations exist across equipment lines.
The engine is the primary power source for the walk-behind trowel or screed, driving the blade rotation or eccentric shaft vibration that gives the machine its working action. On a walk-behind trowel such as the CA4HC or CA5BC, the engine powers the gearbox that spins the finishing blades, controlling surface texture and flatness of freshly poured concrete. On the PSH Protoscreed, it drives the vibrating screed head that consolidates and levels the concrete surface. When an engine loses compression, fails to start, or delivers inconsistent power, blade speed drops, surface finish quality suffers, and the machine becomes unreliable on the pour — replacing the engine assembly with the correct OEM unit restores full working performance immediately.
Part Details
| Part Number | 21387 |
|---|---|
| Brand | Multiquip |
| Part Type | Genuine OEM |
| Description | Engine, 4 HP Honda GX120K1QX2 |
Compatibility & Fitment
| Name | Model |
|---|---|
| Screeds | PSH |
| Whiteman Walk-Behind Power Trowels | CA4HC/CA5BC |
| Power Trowels | CA4.4HM |
| C and CA Series | CA4HC |
| International Walk-Behind Power Trowels | CA-4-4H |
| Whiteman Walk-Behind Power Trowels | CA4HM |
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.
General Equipment
General Equipment Engine, Honda, 4Hp, 3/4"Std.Shaft/Gp8, Net | GX120K1QX2
