Honda Engine Maintenance Guide for a GC190

GC190The GC190 is one of the most popular small engines on the market for lawn and shop equipment, but even an engine as reliable as this Honda needs maintenance to keep performing year after year. This guide will walk you through the steps needed to keep your motor working.


  • Make sure the engine is off before you begin any repairs. If possible, wait at least a half hour to ensure the motor is completely cool to prevent burns from hot engine parts.
  • If the engine needs to be started, do so in an area with good ventilation to prevent carbon monoxide buildup.
  • To prevent gasoline ignition, only use non-flammable solvents for cleaning and keep sparks, flames and cigarettes away from the engine.

Maintenance Schedule

Before each use: Check the engine oil level and air filter

First month or 5 hours: Change the oil

Every three months or 25 hours: Clean the air filter. More frequent cleanings may be needed when used in dusty areas.

Every 6 months or 50 hours: Change the oil. If the engine is always under heavy load or used in high temperatures, change the oil every 25 hours.

Every year or 100 hours: Check the spark plug, clean the spark arrester and have the idle speed, fuel tank, fuel filter and valve clearance checked by a service center.

Every 250 hours or two years: Have a service center check the fuel tube and combustion chamber.


This engine is made to use fresh unleaded with an octane rating of at least 86 and a maximum of 10% ethanol (E10) or 5% methanol. Never fill the tank past the base of the filler neck. Move the engine at least 10 feet (3 meters) away from the refueling location before starting to prevent vapor ignition.


Engine oil should be certified API SJ or later. 10W-30 is recommended, but 5W-30 can also be used at most temperatures, and SAE 30 above 50°F (10°C.)

To check the oil, remove the oil filler cap/dipstick, wipe it clean, and reinsert it in the hole without screwing it in. Check the level on the marks on the dipstick.

To change the oil, place a container below the engine, then remove the filler cap/dipstick, followed by the drain plug, directly below and to the left of the oil fill hole. Once the oil has drained, reinstall the drain plug and add oil until it comes up to the edge of the oil fill hole. Reinstall the filler cap/dipstick.

Air Cleaner

To access the filter, press the latch tabs on the side of the cover and tilt the cover up to remove.

To clean the filter, tap it against a hard surface to loosen the dirt. Wipe away any dirt on the air cleaner body before reinstalling the filter.

Spark Plug

To remove the spark plug, unplug the spark plug wire, then unscrew the plug using a plug wrench.

The spark plug gap should be set to 0.028-0.031 inches (0.70-0.80 mm.) Replace the plug if the electrode is worn, the insulator is cracked, the washer is damaged or the plug head is fouled.

To install the plug, screw it into the engine by hand. Once it’s tight, use the wrench to turn it another 1/8-1/4 turn if the plug is used, or 1/2 turn if the plug is new. Reattach the spark plug wire.

Spark Arrester

Not all GC190 engines have a spark arrester, but one can be installed if it is needed to comply with local fire laws.

To access the arrester, remove the three 6mm bolts holding the muffler protector over the muffler. Remove the protector, then take out the 4mm screw keeping the arrester in the muffler.

Clean the arrester with a wire brush, removing any carbon buildup. The arrester should be replaced if it has any cracks or holes.

Reinstall in reverse order.


Always clean the motor before storage. Never use a hose or pressure washer to clean the engine, as this can force water inside the crankcase.

To prevent oxidation, treat the fuel with a gas stabilizer and fill the fuel tank completely to reduce contact with air. Untreated gasoline should not be used if it is over 30 days old.

For long term storage, all fuel should be removed from the engine. Use a siphon pump to move gas in the fuel tank into a fuel can. To drain the carburetor, remove the drain screw at the base of the carburetor bowl, located behind the air cleaner.

The oil should be changed before storing, and 1-2 teaspoons (5-10 cc) of oil should be added to the inside of the engine through the spark plug hole. Once the oil has been added, pull the starter several times to spread it around the inside of the motor, then reinstall the plug.

Store the engine in a well-ventilated area to prevent the buildup of gasoline fumes. Covering the motor in a non-porous sheet can trap moisture, promoting rust.

Where to Get Parts and Accessories For Your Honda GC190

When you need parts for your Honda small engine, turn to We’re a certified Honda small equipment dealer, and we can ship anything you need to keep your GX190 running whether you’re in the U.S. or Canada. Start your search at our Honda engine section where you can compare applications, part numbers and factory diagrams so you can be sure you’re ordering the parts you need.

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