Biswing Pressure Washer Pump 7/8-inch Shaft Vertical Plunger — 3400 PSI, 2.5 GPM

Biswing’s replacement pressure washer pump is a vertical-plunger, 7/8" shaft unit rated to 3400 PSI and 2.5 GPM for gas-powered cold-water washers.

If your gas pressure washer with a 7/8" horizontal crankshaft has lost pressure or begun leaking, this Biswing pump is built as a direct-fit replacement for many 6.5–7 HP (180–225 cc) engines. The pump combines an aluminum-alloy body with a thermal relief valve, standard garden-hose and M22 fittings, and comes with the common hardware and detergent hose needed for installation. It is designed for cold-water cleaning tasks and optimized for compatibility with top consumer models that accept a vertical plunger pump with a 7/8" drive.

What engine and shaft sizes does this Biswing pump fit?

This pump is intended for engines with a horizontal 7/8" crankshaft and is commonly used on 6.5–7 HP (180–225 cc) gas power washers. Confirm your machine’s shaft size and orientation before ordering to ensure a correct fit.

• 7/8" shaft diameter fits standard horizontal engines
• Best suited for 6.5–7 HP (180–225 cc) engines
• Not for vertical-shaft or electric-only motor assemblies

How much pressure and flow does the pump provide?

The Biswing pump delivers up to 3400 PSI maximum working pressure and flows at 2.5 GPM, giving a balance of force and water volume for heavy-duty residential cleaning. These ratings describe peak performance—actual output depends on your engine’s condition and nozzle selection.

• Maximum working pressure: 3400 PSI
• Flow rate: 2.5 gallons per minute (GPM)
• Performance varies with engine RPM and nozzle choice

Which fittings and accessories come with the replacement pump?

The pump includes the common inlet and outlet connections used by many consumer washers and a selection of mounting hardware to simplify installation. If your hose uses a nonstandard connector, an adapter may be needed (not included).

• 3/4" NH garden-hose style inlet for water supply
• M22-14 male-thread high-pressure outlet for hose connection
• Includes detergent hose, shaft keys, bolts, locknuts, and flat pads

What materials and safety features are built into the pump?

Constructed with an aluminum-alloy housing, the pump aims to be lightweight yet durable while resisting wear around seals and fasteners. A built-in thermal relief valve helps prevent overheating during stalled or restricted-flow conditions to protect internal components.

• Aluminum-alloy pump body for corrosion resistance and strength
• Integrated thermal relief valve to reduce overheat risk
• Designed for cold-water use only; oil/water seals optimized for durability

Who is this for: The Biswing 3400 PSI, 2.5 GPM replacement pump is for homeowners, rental businesses, and light commercial users who need a reliable, direct-replacement pump for gas power washers with a horizontal 7/8" shaft. Choose this pump if you want a durable aluminum-body unit with standard NH and M22 fittings, included mounting hardware and detergent hose, and a thermal relief feature for safer operation during heavy cleaning jobs. Do double-check compatibility with your engine’s shaft orientation, connector threads, and cold-water designation before purchase.