Overhead Cam          > Print chart
7HP / EX21 Fuel Injection
   Performance Curve:
Performance Curve
Performance Curve

Engine Overview:
This is the world's first Electronic Fuel Injection System used on single-cylinder recoil start general-purpose engines.

Engine Family Overview:
With nine models ranging from 4.3- to 14-horsepower, the Subaru Overhead Cam Industrial Engines lead the industry in technology, offering more power, less noise and easy, one-pull starting every time. Introduced as the first air-cooled engine line to use advanced chain-driven Overhead Cam technology, the Subaru EX Series provides maximum efficiency, performance and power with minimal noise and emissions. The engine design is extremely compatible and easy to install, and simply exchanges with most existing slant cylinder engines. 

  Class Air-Cooled Industrial Overhead Cam Chain Drive
  Shaft Horizontal
  Cylinders 1
  Displacement 211cc
  Cycles 4
  Fuel Unleaded Gasoline (min. 87 Octane)
  Max HP/RPM (Gross HP) 7/4000
  Max KW/RPM 5.1/4000
  Max Torque ftlbs/RPM 10.26/2500
  Bore x Stroke mm 67 x 60
  Compression Ratio 8.5:1
  Starter Recoil
  Dry Weight lbs 35.28
  Dry Weight kg 16
  Width inches (mm) 12.6 (321)
  Height inches (mm) 14.5 (369)
  Fuel Capicity US Gallons (ltrs) 13.2 (335)
  Fuel Capacity Fl oz (ltrs) .95 gal
  Lube Type Grade SE or higher 10W-30
  Oil Capicity Fl oz (ltrs) 20.3 fl. oz
  Air Cleaner Foam (optional dual stage paper)
  Muffler (type) Rigid Type Low Noise
  Ignition System Solid State Transistorized Magneto
  Lube System Splash
  Oil Sensor Optional electronic low oil level
  Emission Rating Tier III EPA/CARB
  Color Black Standard
  Governor System Centrifugal Flyweight (optional electronic)
  Fuel System Throttle Body--Electronic Fuel Injection
   Key Features & Benefits:
Air Cleaner Removed This view shows the air cleaner removed and the throttle body's main components.
Cutaway View of Throttle Body This cutaway view of the single piece throttle body gives a description of some of the components and connections.
Cutaway View of Throttle Body This view shows the Delphi Injector in the cavity of the throttle body. This injector is easily serviced.
EX21 With Components Removed In this picture, the flywheel, air cleaner, recoil, throttle body and gas tank are removed to show the main components of fuel injection, power coil and wiring harness.
Aluminum Alloy Die-Cast Connecting Rod The connecting rod is a specially heat-treated aluminum alloy die-casting. Its large and small ends function as bearings. A splasher built into the connecting rod lubricates by splashing engine oil. The piston is an aluminum alloy casting with grooves for mounting compression and oil rings.
Cast-Iron Cylinder Liner Cast-iron cylinder liners enhance reliability and extend engine life.The cast iron cylinder liner has much better wear characteristics than the softer aluminum that surrounds it, making engine life much longer than if the piston is in contact with the aluminum cylinder wall.
Cylinder Head 360-Degree Cooling Head cooling is critically important to long engine life. The Overhead Cam design allows for 360-degree air flow around both the exhaust and intake valve stem areas.
Automotive Collets and Forged Steel Valve Retainers Subaru EX engines use automotive quality collet valve retainers for longer life.
Camshaft with Automatic Decompression Release The camshaft and the sprocket are made of special sintered alloy and constructed as a single piece. The camshaft is provided with intake and exhaust cam in one cam lobe. The decompression release lever is mounted on the sprocket end side.
Dual Ball Bearing Crankshaft Support Dual ball bearing crankshaft support offers maximum stability under demanding loads.
Hardened Steel Rocker Arms Hardened steel rocker arms with precision tappet adjusters are used for greater durability and reduce service requirements.
High Efficiency Intake Port The illustration shows the straight intake port on the right side of the picture. The lower resistance to the flow of the air/fuel mixture improves the power, efficiency and lowers emissions. Overhead Cam (OHC) technology allows the intake and exhaust valves to be positioned for optimum performance.
High Power Pent-Roof Design Overhead Cam (OHC) technology and the Pent-Roof combustion chamber allow the Subaru EX engines to use a higher compression ratio of 9:1. The higher compression ratio increases the power produced for a given size engine. It also improves efficiency and overall performance.
Hot Spark Ignition System The ignition system is a transistor controlled magneto with the ignition timing set at 23 degrees before top dead center. The magneto consists of a flywheel and ignition coil. To ensure the easy startability of the engine, the step advancing ignition timing system is incorporated in the ignition coil. This system enables the engine to have basically two different ignition timings according to the engine speed.
Intake Valve Seal Special machining on cylinder head allows the oil seal to be placed around the valve guide. This seal reduces oil consumption and is replaceable for service.
Mounting Base Cooling Fins The unique Subaru cooling system extends to the underside of the mounting base. Air is forced over special cooling fins at the bottom of the engine for maximum cooling.
Optimized Capacity-Rigid Type Muffler Optimized-capacity rigid muffler and 33 percent fewer moving valve train parts than OHV designs, reduce mechanical noise levels a full 2 decibels below competitive models.
Patent-Pending Connecting Rod Dipper The EX lubrication system begins with patent-pending oil scoop to project the oil to the chain.
Patent-Pending Breather System A patent-pending breather system with a pre-separation
passage prevents oil from spouting even if the engine is inclined.
Patent-Pending Cylinder Cooling Fins Air is forced over the large slanted cooling fins on the cylinder for improved cooling performance. This design is patent-pending.
Patent-Pending Valve Cover Design A patent-pending valve cover design constantly supplies an optimum amount of oil to the cam shaft and rocker arm even if the engine is inclined.
Special Cooling Fins Cooling fins are cast into both the inside and the outside of the crankcase to utilize every possible cooling area.
Spheroidal Graphite Cast Iron Crankshaft The crankshaft is made of spheroidal graphite cast iron, and the crank pin is high-frequency induction hardened. The crank sprocket used to drive the chain, as well as the gear used to drive the governor gear, are pressed on the output end of the shaft.
NO Special Tools Needed Even though the EX series of engines bring the latest technology, performance, and durability to the industrial air cooled engine market, there are no special tools required to work on this engine. Most shop tools that small engine mechanics currently own, will also work on this engine for service or complete tear down. The commitment by the Subaru engineers to 'keep it simple', but use the latest technology was achieved.