Set the boundaries for the types and sizes of engines you will work on. The simplest and most common are air-cooled, one-cylinder, two- or four-cycle gasoline engines. More complex engines are (like most automobile engines) multicylinder, water-cooled plants. Complexity of repair and inventory of parts goes up dramatically when you come to engines with belts, generators, and power takeoffs. You’ll need some special expertise to take on outboard motors and mission-critical systems such as emergency electrical generators.
In doing this kind of home services (specialty), you’ll need to invest in a library of technical manuals for the most common engines. You’ll need a set of small engine tools and you’ll need basic parts and supplies, including spark plugs, engine oil, filters, and gaskets. Based on your customer’s description of the type of engine and its model number, you may be able to purchase parts as needed. If you will be operating a mobile repair service, you’ll need a vehicle large enough to carry your tools and supplies. You should be able to work with a small van or a station wagon. You can add a trailer hitch and a small trailer if you need to transport an engine or an entire machine back to your workshop. Other expenses include advertising and promotion.
For the cost of this service, you can charge by the hour, plus the cost of parts (marked up from wholesale) for standard repairs. For basic maintenance, you can set a flat fee for particular classes of engines—for example, for a tune up of a lawn mower or chainsaw.