Honda GC135 Operation and Troubleshooting Guide

There’s a vast range of small engine equipment out there, but Honda’s legendary reliability means their engines can be found powering just about everything. The GC135 is no exception, and using it is the same no matter what is attached to the output shaft. This guide will walk you through running this engine, as well as solving common problems so you can keep your equipment working year after year.

Adjustable vs Fixed Speed Engines

The GC135 comes in two versions: fixed and adjustable speed.

Adjustable speed engines will have a gray throttle lever above the recoil starter, or a remote throttle control on the handle of the device the engine is powering. Moving the lever up opens the throttle, while moving it down to its lowest position will shut off the engine.

Fixed speed engines will have a red ignition switch lever above the recoil starter. If the lever is pointed up, the ignition is on, and if it’s down, the ignition is off. Like the throttle lever, some equipment will have the control mounted remotely on the handle.

Before Starting

Check the area for oil and fuel leaks, and clean off any dirt, especially around the muffler and starter.

Move the engine to a level surface. Check the oil by removing the dipstick, wiping it off, and inserting it back into the filler neck without screwing it into the motor. Pull it back out: if the stick is dry, more oil needs to be added to the engine.

Check the air filter: push the two tabs on the filter cover and flip the cover up. If the filter is damaged, replace it before starting the motor.

Make sure the ignition switch is off or the throttle lever is in the stop position.


The choke rod is located next to the filler neck of the gas tank. If the engine is cold, pull the rod out to close the choke. If the engine is warm, push the rod in to open the choke.

On adjustable speed engines, move the throttle lever about 1/3 of the way above the “Slow” mark. On fixed speed engines, move the ignition switch to “On.”

Pull the starter handle gently until you feel resistance, then give it a quick tug. The engine should start.

Once the engine is warm, push in the choke rod in to open the choke. Adjust the throttle (if equipped) to set the engine speed to power the equipment.


On adjustable speed engines, move the throttle to “Stop.” On fixed speed engines, move the ignition switch to “Off.”


Engine Won’t Start

  • Make sure the ignition switch is set to “On” on fixed speed engines. Close the choke if the engine is cold.
  • Make sure there is fresh gasoline in the fuel tank.
  • Check the spark plug. If it’s wet, the engine is flooded: wipe down the plug and reinstall it. Make sure the spark plug gap is between 0.028 and 0.031 inches (0.70 to 0.80 mm.) Replace the plug if the electrode is worn down or there is other damage to the plug.

Engine Lacks Power

  • Make sure the throttle is set high enough on adjustable speed engines.
  • Check the air filter. Clean or replace it if it’s clogged.
  • Check the fuel. If it’s old, drain the tank and add fresh fuel.

If these steps don’t address the problems you’re having with the motor, take it in to a service center for inspection.

Draining Fuel from the Engine

Like most small engines, the GC135 is sensitive to fuel quality. Over time, untreated fuel can oxidize, reducing its combustibility.

To drain the carburetor, loosen the drain screw, located in a recess below the choke rod. When opened, fuel will drain out of a hole at the base of the carburetor: to reduce spills, slide a piece of hose over the opening and run the other end into a fuel container.

To drain the fuel tank, use a siphon hose to draw gas out of the tank and into a suitable container.

Sourcing Parts

Do you need a spark plug or an air filter for your GC135? You can get these parts and more from We’re a certified Honda small engine equipment dealer, so we carry everything for these motors from the smallest bolt to pistons and other major components. Finding what you need is easy, too, thanks to our advanced search engine that lets you match parts up with factory diagrams and descriptions. We can ship these parts to any address in the U.S. and Canada.

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