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Small Engine Maintenance

The small gasoline engine is employed for a myriad of tasks on the farm. For the most part, they are dutiful soldiers. That is, if you can get them to run. By far, the most common complaint is either hard starting or not running at all, which is a frustration we’ve all experienced. Here are pointers on how to keep a small engine starting easily.

Carb is the heart
By nature of their size, these engines are simplistic in design, consisting of a carburetor and (if a pull-start is employed) a modern version of a magneto to produce spark.

The majority of issues are related to the carburetor, a component that is tasked with atomizing the gasoline so that it will ignite.

Three things need to happen to gasoline before it can run an engine: It must atomize (break into small particles), emulsify (mix with air), and vaporize (have a phase change from a liquid to a gaseous state).

The carburetor is responsible for the first two steps, while Mother Nature, through heat, takes care of the last task by using the latent heat of vaporization.

If the carburetor does a poor job of atomizing the fuel, all of the other steps skew, and the engine is hard starting or will not run. A good indicator of this is a wet spark plug. Once this happens, the electricity uses the fuel for a path to ground instead of jumping the gap.

Carbs do come loose
Since the engines vibrate, it is important to keep all fasteners that hold the carburetor together and to the intake manifold or cylinder snug. Many designs use a rubber boot that connects the carburetor to the cylinder head and, over time, it gets hard and cracks. An early sign is difficult starting and an objection to idle.

When an induction system has an air leak between the carburetor and the cylinder, the signal becomes weakened or is completely lost. This describes the low pressure created by the piston to draw fuel through the carburetor.

The carburetor needs to be washed with a carburetor spray for good functioning, and be sure to keep its air filter clean.

Keep in mind that a tired engine with worn piston rings and valves will not allow a strong signal to be created and will be extremely hard starting with a pull rope.

When faced with a problem, first check for spark, and then pull the plug and examine it.

If it’s wet, there is fuel, but it isn’t being atomized properly.

If it’s dry, then either a circuit is dirty in the carburetor or the ring seal is so poor in the cylinder that no signal is being created to pull fuel.

Many engines become hard starting and unusable if they haven’t had regular oil changes.

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