Subaru Robin Power Products EH12-2, EH17-2, EH25-2 manual Automatic Decompression System

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7.AUTOMATIC DECOMPRESSION SYSTEM

EH12-2, 17-2, 25-2 engines are employing the automatic decompression systemas a standard feature. This enables easy and light startof the engine. Theautomaticdecompressionsystemreleasesthecompression of theengine by liftinguptheexhaust valve at the cranking. Following are the explanation using type “D”engine as a sample how the system works. The components of the systems are different for the type “D” and type “B” engines, however, the principle of the function is same.

At the end of the compression process, the release lever lifts up the tappet which in turns opens up the exhaust valve slightly to release the compression. The release lever has a flyweight on its end and another end of the lever is a crescent cam.

When the engine is cranked, the crescent cam projects the camshaft cam profile and lifts up the tappet because the gravity force on the weightis larger than the centrifugal forceon the weight.

iTAPPET,I

LEVER

CRESCENT

EXHAUST

Fig. 7-1

When the crank speed reaches up to a certain revolution, the crescent cam is retracted into the camshaft cam profile because the centrifugal force applied onto the flyweight becomes larger than the gravity force and the weight.andis shifted to the position shown in the illustration.

FLYWEIGHT

LEVER

CRESCENT CAM

EXHAUST-YCAM-T3

 

EXHAUST CAM

,”-

 

CAMSHAFT

 

 

Fig. 7-2

 

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Contents Page Contents Page Specifications EH17-2 EH25-2 2 5 2 6 s EH25-2D EH25-2DS 1MAXIMUMOUTPUT +3l2 Kgfam 3000 Features Crankshaft is forged carbon steel, and the crank 6CAMSHAFT 9GOVERNORSYSTEM To effectively reduce vibration Decompression System 17SECTIONAL View of Engine Rocker ARM Push ROD Disassembly and Reassembly Disassemblyprocedures Fuel tank Close fuel valve Recoil starter Housing Oil sensor Option 1pc. EH25-2 Starter 2pcs Procedures Remove starterpulley from flywheel M6 X 25mm Screw Procedures Remarks Fastening Be careful not to damage Step Remove piston rings from piston Be careful not to damage Intake valve Loosen nut and remove bolt pivot Inspect Valves 4REASSEMBLY Procedures Precautions for Reassembly Valve Recess 54-4CONNECTING ROD Tappet Andcamshaft Spacer Shims EH12-2,17-2 Ft4b Spark plug 54-16GOVERNOR System Refer to the illustrations below. SeeFig Install the muffler to the cylinder head Flange nut ... pcs Ignition System 1000 3WIRING Diagram Automatic Decompression System Carburetor 21 -@ Float System Starting System CbI Do not abruptly put off your Page IO. Troubleshooting 10-1-3IGNITIONSYSTEM 10-5ENGINE Knocks Installation Service Data STD Lmit Uni rnm STD Limit EH12-2 STDLimit EH17-2 LTEM Valve Limit 3134 EH25-2 Description Tightening Torque 12-3OIL Grade Chart Maintenance and Storage Clean fuelfilter and fuel tank Page SU6ARU

EH12-2, EH17-2, EH25-2 specifications

Subaru Robin Power Products has established a reputation for quality and reliability in the world of small engines, especially with their EH Series engines: EH12-2, EH17-2, and EH25-2. Each of these models brings unique benefits and advanced technologies, catering to various applications for both commercial and personal use.

The EH12-2 is a compact engine designed for lightweight applications. Weighing in at just 66 pounds, it is ideal for portable equipment and general-purpose applications. Its 4-stroke design allows for lower emissions and greater fuel efficiency compared to traditional 2-stroke engines. The EH12-2 features a low-profile design that enhances stability while operating. Its overhead cam design enables better performance at higher RPMs, making it ideal for tasks that require consistent power and reliability.

Moving up in size, the EH17-2 boasts a more robust configuration, making it suitable for semi-professional applications. With a displacement of 169cc, this engine provides higher torque and improved performance for heavier machinery. The EH17-2 also incorporates Subaru’s advanced air filtration technology, which extends engine life and reduces maintenance frequency. This engine is particularly suited for applications such as generators, pressure washers, and other equipment requiring sustained power output.

Finally, the EH25-2 stands as the powerhouse of the series. With a displacement of 252cc, it delivers exceptional torque and horsepower for demanding tasks. The EH25-2 employs Subaru's patented electronic ignition system, offering easy starts and consistent performance in a range of conditions. Its multi-point lubrication system ensures that all engine parts receive adequate oil, resulting in reduced wear and tear over time. Additionally, the EH25-2's rugged construction is designed to withstand vibration and strain, making it ideal for construction and heavy-duty industrial applications.

All three engines share core features such as a user-friendly design, efficient fuel consumption, and compliance with environmental regulations. The engines are also equipped with easy-access maintenance points, helping users perform necessary upkeep without hassle. Whether for a homeowner with occasional needs or a contractor relying on dependable machinery, Subaru's EH series provides powerful and efficient solutions tailored to meet varying demands. With their focus on innovation and quality, Subaru Robin Power Products continues to evolve and improve, ensuring their engines serve diverse markets effectively.
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