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Tkart magazine

How To | All the steps to… overhaul the starter motor

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21 March 2018
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It is a fundamental component on engines equipped with an electric starting system. What are we talking about? The starter motor, obviously, the component tasked with transforming electrical energy into mechanical energy and starting the kart engine. An electric starting system is undoubtedly convenient, especially when compared to the push-start system used on the old 100 cc direct drive engines, but involves a series of components that are subject to wear.

That is one of the reasons why the OK engines do not have an electric starting system, but there are lots of classes that still use this convenient solution. So, let’s take a look at how to carry out the maintenance of the starter motor, how to clean it and replace the brushes.


As happens with all “additional” parts, having a starter motor implies the having one more component that can undermine a kart’s efficiency and, therefore, must be kept under control. Its weakness, which causes the most problems, are the brushes, which are subject to particular wear after a considerable number of starts. In general, failure occurs in the filament of the brush and there is no way to predict this happening with any precision. However, it is possible to understand when wear starts to become excessive by paying attention to the warning signs.
For example, when the battery runs down much faster, as much as halving its autonomy.

This occurs because the section of the filament of the brushes decreases, creating a resistance that can lead to failure.
A second sign that the starter motor is not working properly is when the kart engine does not start first time, but requires more time and the start-up is not as prompt.
Another sign is when the starter motor shows no signs of life and only starts working if the power cable is moved around or the starter motor itself is tapped a few times. That is a clear symptom that the brushes need to be replaced.


In order to perform an overhaul, the first operation is to remove the engine from the chassis, in order to facilitate the disassembly of the starter motor. Each type of engine has its own attachment, but usually removing just a few screws allows you to free the starter motor.

As far as the actual starter motor is concerned, start by removing the power cable by simply unscrewing the attaching screw using a cross-head screwdriver. For convenience, the starter motor can be held by the vice on the side of the gears, making sure to use clamps made of "soft" material and not to tighten too much, which would ruin the teeth of the gears.

Then, also use a cross-head screwdriver to remove the screws that attach the body of the starter motor to its base. A tip is to loosen all the screws first and, then, unscrew them completely.

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