Powerease R420-18A Electric Start Engine – 420cc, 12.6 HP, 1" Horizontal Shaft

Part Number: 85.578.150
Category: Small Engines
Type: Powerease R420-18A Electric Start Engine – 420cc, 12.6 HP, 1" Horizontal Shaft

The Powerease R420-18A Electric Start Engine is a heavy-duty 420cc OHV gas engine engineered for demanding commercial and industrial applications. Delivering 12.6 HP at 3,600 RPM and 17.8 lb-ft of torque, this engine provides dependable, continuous power for equipment that operates under sustained load.

Featuring recoil and electric start with key system, an 18-amp charging system, and automatic low-oil shutdown, the R420-18A is ideal for pressure washers, water pumps, air compressors, and construction equipment. Its efficient OHV design runs cooler and cleaner, improving fuel efficiency while extending engine life.

Key Features

• 420cc air-cooled, 4-stroke OHV engine

• Net power output: 12.6 HP (9.4 kW) @ 3,600 RPM

• Net torque: 17.8 lb-ft (24 Nm) @ 2,500 RPM

• Recoil & electric start with keyed ignition

• 18-amp charging system

• 1" keyed horizontal shaft (counterclockwise rotation)

• Dual-element air cleaner for dusty environments

• Automatic low-oil shutdown for engine protection

• Splash lubrication system

• Built for continuous-duty operation

Engine Specifications

• Model: Powerease R420-18A

• Displacement: 420cc

• Bore x Stroke: 88 mm x 64 mm

• Compression Ratio: 8.2:1

• Net Power Output: 12.6 HP @ 3,600 RPM

• Net Torque: 17.8 lb-ft @ 2,500 RPM

• Starting System: Recoil / Electric (keyed)

• Ignition System: Transistorized Magneto

• Carburetor: Horizontal type butterfly valve

• Lubrication System: Splash

• Low Oil Shutdown: Yes

• Fuel Type: Regular unleaded 86 octane or higher (ethanol blends up to 15% acceptable)

• Fuel Tank Capacity: 6.7 L (1.77 gal)

• Oil Capacity: 1.1 L (1.16 US qts)

Shaft Specifications

• Shaft Orientation: Horizontal

• Shaft Rotation: Counterclockwise

• Shaft Size: 1" keyed

• Keyway Size: 1/4" x 2.2"

Dimensions & Weight

• Dry Weight: 70 lbs

• Package Weight: 77 lbs

• Unit Dimensions (L x W x H): 17" x 18" x 18"

• Shipping Dimensions (L x W x H): 21" x 17" x 20"

Built for Tough Applications

The R420-18A is engineered for equipment requiring reliable torque and extended run times. Its air-cooled OHV design improves thermal efficiency, reduces fuel consumption, and minimizes wear—making it ideal for professional, daily-use equipment.

The 1" keyed horizontal shaft allows compatibility with a wide range of machines, making this engine an excellent option for both new builds and replacement applications.

Field-Serviceable Design

Service components such as the air filter, carburetor, and spark plug are easily accessible for quick maintenance. The dual-element air filtration system provides enhanced protection in dusty job-site conditions, while the low-oil shutdown system helps prevent costly engine damage.

Typical Applications

• Pressure washers

• Water pumps and dewatering systems

• Air compressors

• Lawn and garden equipment

• Construction and job-site machinery

• Industrial equipment requiring continuous power