Detachable cylinder heads secure with four cap screws or long studs that thread into the crankcase. Loosen in an X-pattern. Rusted threads can bind the nuts to their studs with the result that the studs unscrew from the crankcase. If this happens, unthread the nut while holding the stud in a softjawed vise. (A pipe [...]
Critical fasteners, such as those that hold the cylinder to the crankcase, should be secured with a few drops of medium-strength anaerobic adhesive, such as Loctite 242 (blue). Locktite 222MS (purple) is appropriate for 1/4-in. and smaller fasteners. These and equivalent “chemical lock washers” from Omnifit, Prolock, and Hernon develop considerable force as they cure [...]
Handheld equipment relies upon a mixture of fastener types. Critical components, such as mufflers and cylinder barrels, secure by cap screws, almost always metric. An M8 screw has a diameter of 8 mm, one thread per millimeter, and a length of 15 mm. The relatively coarse 1-mm pitch is standard for makeup to aluminum. One [...]
Single main-bearing engines that combine the cylinder and crankcase into a common casting come apart easily (Fig. 6-3). Vertically split crankcases may be a bit difficult to separate, since the main bearings and alignment pins make interference fits with the casting halves (Fig 6-4).
Major engine repairs are initiated by weak compression, crankcase leaks, and other obvious signs of distress, such as a scored piston or a rattling connecting rod. Tests If an engine develops normal compression and the crankcase holds air pressure, the rod and main bearings are probably okay. Cylinder Compression Handheld engines should develop at least [...]
Preload, or the spring tension necessary to fully retract the cord, can be achieved in either of two ways. Without the cord handle attached: 1. Secure one end of the cord to the sheave. Some manufacturers provide an anchor, others rely upon a nonslip knot. 2. Wind the cord completely over the sheave so that [...]
The replacement starter cord, or rope, should have the same diameter, length, and weave as the original and it should be made of unalloyed nylon. If the length is unknown, secure the cord to the sheave and wind until the spring coil binds. Allow the sheave to unwind for one or two turns and cut [...]
Replace the spring if broken, distorted, or too weak to retract the cord. Otherwise, leave it undisturbed. Replacement springs usually are prewound. Some come housed in a retainer and install as an assembly. Others are secured by a wire clip, reminiscent of the loading clips used on the old M-1 rifle. Align the outboard spring [...]
The sheave, also known as pulley or rotor, is secured by a central screw or by tabs around its rim. Once the hold-downs are removed, the sheave lifts off to expose the main spring. The trick is to lift the sheave without dislodging the spring from its housing. Should this happen, the unconfined spring lashes [...]
Before dismantling a starter, the main spring must be allowed to uncoil as much as the housing permits. It will still contain energy. Disarming is accomplished either by detaching the cord handle or by partially disengaging the rope from the sheave. The handle can be removed by untying the knot or by cutting the cord. [...]
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