Tools Needed To Repair Small Engines
You don't need to have a lot of tools to repair small engines. Aside from basic hand tools, you'll need a few specialty tools, plus a few testing tools that you may already have. What you'll need will depend on how deep you're going into the motor.
Testing Tools
On a used single-cylinder engine in decent shape, 60 psi is good compression. For checking engine compression, you'll need an engine compression gauge.
Hand-held engine compression tester with quick-release.
Compression Tester
The two common varieties of compression gauge will have either a rubber tip (that you need to hold down) or a thread-in fitting that goes into the spark plug hole.
Ignition Testing Tool
There's several ways to test for spark, but I find this Briggs & Stratton spark tester to be fast and easy to use.
Engine Tachometer
A tachometer is needed to verify engine RPMs.
This simple Briggs & Stratton tachometer works by picking up vibrations from the motor. It will work on most small engines, including magneto-equipped flatheads, Honda GX series, and 420/460cc clone motors. It will also work on V-Twins such as the Briggs Vanguard and Predator 670cc.
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Specialty Tools
Removing Valves On A Tecumseh Flathead Engine
Valve Spring Compressor
A valve spring compressor like this Lisle 23300 works well with many small engines. It's designed to handle 3/4" to 1-1/16" valve springs. Two bottom arms are included with the tool; the extra one has a smaller opening for a tighter fit.
Three-Jaw Puller
The many uses of a three-jaw puller include flywheel removal. Prying off a small engine flywheel with a screwdriver is not recommended.
Other Specialty Tools
- Piston Ring Compressor
- Torque wrench in inch-pounds
- Torque wrench in foot-pounds
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Engine Measuring Instruments
An important step in a complete engine rebuild is inspecting and measuring worn parts. Although most of us are more mechanics than machinists, the need sometimes arises to precisely measure clearances, wear, and play.
Feeler Gauge
A feeler gauge, or gap gauge, is used primarily for checking ignition point gaps and valve tolerances. They are made up of thin metal blades, and each blade is a different width of precise thickness. These are marked in either thousandths of an inch, or millimeters.
The blades usually range from .0015" to .035" (.038 to .889mm). Long feeler gauges may be needed for valve adjustments on some engines.
Dial Bore Gauge
To accurately measure the inside diameter of a cylinder, a bore gauge is needed. The bore gauge I have is a ToolUSA TM-34260. It covers two to six inch bores, has a bore depth of six inches, and the dial has .001" increments.
Shop: Dial Bore Gauge
Just as important as good measuring equipment is the ability to use these tools correctly. These include measuring devices such as a micrometer, dial indicator, dial bore gauge, and a feeler gauge.
Digital Caliper
Essential to precise engine building is a quality caliper. Dial calipers are less expensive than digital calipers, but digital ones have an LCD display for easy reading.
Remember that micrometers, dial indicators, and dial bore gauges are precision measurements, and need to be treated as such. For consistent and reliable results, keep them clean and out of harm's way.
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Hand Tools
If your American-made engine was manufactured prior to 1980, "standard" tools will probably suffice, no metric tools needed. Chances are you already have some basic hand tools. These should include:
Box End/Open End Wrenches from 1/4" to 1" (Shop)
Combination Wrenches 7/16" to 1" (Shop)
Combination Wrenches in Metric (Shop)
Screwdriver Set (Shop)
Hammers (Shop)
Ratchets in sizes 1/4", 3/8", and 1/2" (Shop)
Breaker bar in 1/2" (Shop)
Six-point sockets from 7/16" to 7/8" and 12mm to 19mm (Shop)
Deep-well Sockets (Shop)
Socket Extensions in three drive sizes from 1-1/2" to 12" (Shop)
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Inexpensive Tool Kit
If you're just starting out, Dewalt makes a good mechanics tool kit for the money. It's a 142-piece set that has three different sizes of ratchets and plenty of wrenches. Also included is a driver set. Built into the case is a neat little storage box for any extra bits and pieces you may end up with.
Shop: Dewalt Mechanics Tool and Socket Set
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Most small engines were designed to be fixed by their owners, but there are several tools that may be a bit out of reach for the average DIYer.
Valve Face Cutting Tool
On a small engine, the valve widths are usually smaller than an inch. Neway offers valve seat cutters individually as well as in master mechanic kits.
I contacted the Neway company directly and they were kind enough to advise me on what I needed. They make valve cutting tools for every engine size out there!
Shop: Neway Valve Seat Cutters
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