Honda Mini Four Stroke Engine

Honda Mini 4-stroke engineHonda’s GX25 and GX35 mini four-stroke engines are built to operate in any position, making them an enticing alternative to hard starting, fuel swilling two strokes. Here’s what you need to know to operate and maintain one of these unique engines, whether it’s powering a string trimmer, a tiller or a water pump.

Starting a Cold Engine

  1. Set the throttle 1/3 of the way above “Slow.” This lever will either be on the engine or the handle of the equipment you’re using.
  2. Move the choke lever, located next to the air cleaner, to the “CLOSED” position.
  3. Press the priming bulb, located next to the choke, until fuel can be seen inside the bulb.
  4. Turn the engine switch, located on the opposite side of the choke and priming bulb, to “ON.”
  5. Hold the starter grip and pull the recoil starter straight out from the opening in the flywheel cover. On tillers, the starter should be pulled straight back, toward the handle. On other engines, your left hand should be holding the starter grip, while your right hand pulls the starter toward you.

Starting a Warm Engine

On tillers and pumps, perform the following procedure before trying to restart the motor:

  1. Make sure the engine switch is in the “OFF” position.
  2. Set the choke lever to “OPEN.”
  3. Set the throttle to the “MAX” position.
  4. Pull the starter 3-5 times.

All engines can be started using the “Starting a Cold Engine” method above, but with the choke open.

Oil

These engines are able to work at any angle because they use a rotary slinger that turns the oil into a fine mist during operation, letting it lubricate in much the same way the oil/fuel mixture does in a two stroke. Because of this, changing and maintaining the oil is a little different from other small engines.

The oil should be checked when the engine is off and sitting level. Check the oil before each use. If you’re using the engine continually, check the level every 10 hours. Wipe the dipstick/filler cap clean, then insert it into the engine without screwing it in. The oil should come up to the bottom mark on the dipstick.

The oil should be changed after a month or 10 hours of use, then every 6 months or 50 hours after that. To drain the oil, simply remove the oil filler cap and tip the engine over a recycling container. Some oil will still be inside the motor, so there’s no standard amount of oil that needs to be added; start by adding 2.7 oz. (80 ml) of oil, then slowly pour in more until the oil is at the edge of the filler neck.

Honda recommends using pump engines at temperatures between 41 and 104°F (-5 to 40°C) and other engines between 23 and 104°F (-5 to 40°C.) 10W30 oil is recommended for most operating conditions, but SAE 30 can be used at temperatures above 50°F (10°C.) 5W30 can be used at temperatures below freezing.

Air Cleaner

These engines use a foam filter element. To reach the filter on tiller engines, squeeze the upper and lower tabs on the cover to lift it off. On other engines, squeeze the tabs on the top of the cover and swing it down. To clean the filter, wash it in soapy water or a non-flammable solvent. Once the filter is dry, soak it in clean engine oil and squeeze out any excess. Wipe out the inside of the air filter box before reinstalling the filter. Honda recommends cleaning the filter every three months or 25 hours.

Accessing the Engine

To get to the spark plug, spark arrester and cooling fins, remove the 5 mm bolt at the top of the engine and slide off the plastic cover. The fins should be cleaned every three months.

Spark Plug

The plug gap should be between 0.60 and 0.70 mm (0.024-0.028 inches.) When installing, always start by screwing the plug in by hand before tightening it with a plug wrench or socket to avoid cross-threading. The spark plug should be checked once a year or 100 hours of operation and should be replaced every two years or 300 hours of operation.

Spark Arrester

Depending on the model, the spark arrester can be accessed by removing a single screw on the muffler where the exhaust exits, or by removing three screws from the exhaust outlet. If the arrester is tube-shaped, it can be cleaned by squeezing and tapping it to remove the carbon deposits. All other types should be cleaned with a wire brush. The arrester needs cleaning every year or 100 hours.

Fuel Filter and Tank

The fuel filter and tank should be inspected and cleaned every year or 100 hours. To reach the fuel filter, use a hook to pull it out of the tank. If the filter or tank are dirty, clean them with a non-flammable solvent.

Getting Parts for Your GX Mini Four Stroke

Hondalawnparts.com is a certified Honda Small Engine Equipment dealer, which means we have everything for these engines from plugs to piston rings. We can ship anything you need to any address in the U.S. and Canada.

Honda iGX Engine Overview

Honda iGX EngineThe electronically-controlled Honda iGX has been making its way into a wide range of equipment including Honda’s own EM and EB series generators. At first glance, it’s easy to confuse a Honda iGX motor with their GX Series, found in pretty much every piece of commercial-grade small engine equipment. That’s understandable since the iGX is a GX at its core, but the iGX has some unique features that change how you need to operate and care for these motors.

What Makes an iGX engine different?

The iGX is based on the GX Series engine, the same design that has been a cornerstone of small engine equipment across the industry, used in everything from generators to pressure washers.

The biggest change is the Electronic Control Unit (ECU.) It can read engine conditions and adjust the governor and throttle, keeping the engine at just the right speed to meet current load demands. The result is fast power response and up to a 15% increase in fuel economy. It’s no wonder that these engines first saw use in generators.

These engines also use CDI ignition with variable timing and a rev limiter. By varying ignition with engine speed, these motors can produce more power over a wide RPM range.

Low Profile Models

For equipment where space is at a premium, Honda offers low profile versions of these engines. These are easy to identify by the large plastic panel next to the recoil starter. This is the cover for the air cleaner. The muffler is located at the rear of the engine, while fuel is stored on the equipment itself instead of a tank bolted to the motor.

The Honda Oil Alert System

The Oil Alert system is designed to protect the engine if it doesn’t have enough oil to stay lubricated. It works a little differently on the iGX than it does on other Honda engines: on some motors, the ECM, located directly above the carburetor, has a small LED light. If it flashes twice, the Oil Alert system has been triggered. On other models, the Oil Alert light is clearly visible next to the ignition switch and will either blink continuously or stay on once the system has been triggered. Most models will shut down to protect the motor, but if a shutdown may be dangerous due to the type of attached equipment, the motor may keep running. If you see the light come on, try to shut down the motor as quickly and safely as possible. Add more oil as needed before starting the engine again.

Starting the Engine

To start an engine with electric start, turn the ignition switch to “Start.” On these engines, the choke is engaged automatically. If it doesn’t start after 5 seconds, release the switch and wait 10 seconds before starting again. If it refuses to start, switch the manual start lever, located next to the ECM, to “On.” Turn the ignition to “On,” then use the recoil starter to start the engine. Don’t move the manual start lever until shutting down the motor.

To start an engine without electric start, locate the fuel lever (lower lever) and choke lever (upper lever) on the carburetor. If you have a low profile engine, which places the muffler and air cleaner behind the engine instead of above it, there will only be a choke lever. If you have an iGX270 or 390, the choke is automatic, so the sole lever is for fuel. Set the fuel lever to open and the choke to closed, as applicable. Turn the ignition switch to “On” and use the recoil starter to start the motor.

Fuses

One or more automotive fuses are used to protect the motor’s electrical system. These fuses are in a clearly marked fuse box on the side of the iGX440, while other motors will have an in-line fuse behind the ignition switch panel on electric start models. A burnt fuse will keep the engine from starting.

Low Power at High Altitude

It should be no surprise when engines make less power at higher altitudes due to the thinner air, but in the case of these engines, this loss in power is due to an incorrect fuel mixture. Honda recommends having the carburetor set up for high altitude use if your motor spends most of its time running at altitudes above 5,000 feet (1,500 m.)

Engine Identification

The serial number and engine model on any iGX can be found on the crankcase directly above the oil drain plug.

Getting Parts for the iGX

www.hondalawnparts.com is a certified Honda Small Engine Equipment dealer, carrying everything you need for Honda small engines and equipment from older lawn tractors to advanced powerplants like the iGX. Our site makes finding parts easy thanks to factory parts diagrams and information built into our search engine. We can ship your order to any address in the U.S. and Canada.

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