Motorcycle Engine Tools
Aside from basic hand tools and a torque wrench, other tools needed to rebuild a motorcycle engine include a micrometer, dial indicator, feeler gauge, piston ring installer, and some specialty tools for your make and model. Other things you should have is a digital camera, curiosity, time, and common sense.
Engine Measuring Tools
One of the first steps of proper engine repair is accurately inspecting and measuring worn parts. Although most of us are more mechanics than machinists, the need arises during a motorcycle engine build to precisely measure wear and play.
I cannot overstress the importance of having good measuring equipment, as well as the skill to use those tools correctly. These include measuring devices such as a micrometer, dial indicator, dial bore gauge, and a feeler gauge.
Essential to engine building is a quality micrometer (also known as a caliper). Digital micrometers are more expensive than dial calipers, but they are quicker and have an LCD display for easy reading.
Engine bearing clearance is crucial, and learning to correctly read a micrometer takes some time. Experienced mechanics always double-check their specs. First-time builders should measure a few dozen times or so before trusting their readings.
Having a dial indicator allows you to check end play, flywheel run-out, up-and-down movement on connecting rods, and many others. Most have increments of .001" with a 0" to 1" scale. They can be mounted by clamp or magnetic base.
Dial Bore Gauge
To accurately measure the inside diameter of a cylinder, a bore gauge is needed. The one I have is a ToolUSA TM-34260. Bore range is two to six inches, has a bore depth of six inches, and the dial has .001" increments.
shop Dial Bore Gauge
A feeler gauge, or gap gauge, is needed for checking valve tolerances, ignition point gaps and other critical measurements. They are made up of thin metal blades. Each blade is a different width of precise thickness, and will be marked in either thousandths of an inch, or millimeters. The blades usually range from .0015" to .035" (.038 to .889mm).
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 harms way.
read Motorcycle Lift Stand Comparison
Cylinder Boring and Honing
If you're restoring an old engine, boring a cylinder back to round requires removing anywhere from .003" to .010" or more of metal. Professional machine shops have large, expensive, dedicated machines to perform all kinds of cylinder boring. The same process can be done in your home garage, but will take considerably more time. By using a rigid honing device and a slow-speed drill, high-quality motorcycle engine cylinder boring is possible.
read DIY Motorcycle Cylinder Boring
Piston Ring Expander
At one time or another, most of us have been guilty of installing rings into the piston grooves by hand, merely to save time. But it's not a good idea, because the rings can get deformed by the twisting action, which may cause sealing problems. A piston ring expander is an inexpensive tool.
Piston Ring Installer
To install pistons back into the cylinders, a piston ring installation tool is needed. A clamp-style ring compressor is the least expensive style, but consider investing in a piston ring installer set. Most sets includes a half a dozen popular sizes you can use for other engine projects.
DIY Engine Tools
If you don't have all the tools needed for your motorcycle engine build, you can either borrow them or buy them (new or used), but many can be fabricated.
Flywheel Truing Stand
A length of C-channel stock is the base of this DIY flywheel truing stand. The two uprights were from an old warehouse shelf. Dial gauges are set up on both sides.
Accurate use of a dial indicator requires rigid mounting and stability. Clamp firmly to a surface as close as possible to the shaft. An adjustable magnetic base allows more options as to where it can be mounted. Position the indicator so the stem is parallel to the direction of component motion.
Flywheel Centering Jig
The picture below shows a flywheel centering jig, made out of pieces of C-channel stock. Each piece was cut four inches in length with a hole drilled in each. A length of threaded rod goes through them. The wing nut on the end is from a spare tire holder.
Flywheel Holding Jig
On many old bike engines, crank-pin nuts must be accurately torqued to 150 ft-lbs. Classic Harley Big-Twin flywheel nuts are torqued to 175 ft-lbs. The engineers who designed those old flywheels put holes in them for a reason, to allow you to slip them over a jig while tightening the nuts.
Motorcycle Engine Stand
If you'll be working on your engine for a while, a stand is invaluable. This DIY motorcycle engine stand was made from scrap metal I had around the garage. The angle iron was cut from an old bed-frame. A couple of 3/16" metal plate scraps provide good strength for the sides.
I built this engine stand to hold a Harley-Davidson Flathead, but will also accept Harley Big-Twins 1936 to 1999 (Knucklehead, Panhead, Shovelhead, and aftermarket engines). Sportster engines are different and won't fit.
DIY Bearing Puller
This is a tool I made to remove the inner sprocket shaft bearing on a 1965 Harley Sportster XLCH. Materials needed were a piece of 2" metal tubing, a 7/16" SAE nut and bolt, and two heavy washers.