The ignition systems used on Homelite chainsaws are electronic modules. These modules house a coil that builds and holds a high-voltage electric spark. When the charge builds to its peak, it’s released up a lead wire to the spark plug for combustion. Due to the high, potentially lethal voltage involved in these ignition systems, don’t try to repair or disassemble them without taking the proper safety precautions.
The Homelite ignition system is called a one-piece capacitor discharge system. The coils in these systems act like the capacitor, holding the charge. The flywheel on the starter has two magnets. When these magnets connect to the arms of the ignition module, a spark is generated and the capacitor, or coil, discharges the spark up to the plug. These ignition systems are standard on most modern chainsaws.
The spark plugs need a gap of .025 inches to function properly. If this gap is off or the metal tip is corroded or bent, the spark can’t fire a sufficient charge to ignite the fuel. The type of spark plug used in Homelite chainsaws is a standard two-cycle engine plug; any brand will be sufficient as long as it meets the gap recommendations.
The timing on Homelite ignition systems is fixed and can't be adjusted. On Homelite chainsaws it’s set to 27 degrees before top dead center, which refers to the piston's stroke on the crankcase. Since no internal wear can happen on the timing, you won’t need to worry about adjusting it. However, certain connection problems can occur at the switching point, such as loose or faulty wires, which will cause the spark to be out of time.
The air gap on the ignition system is the distance between the flywheel’s magnets and the ignition module. This helps to make sure the spark is fired at the right time. If this gap is off, the spark may still fire but at the wrong time and with the wrong amount of voltage. The air gap for Homelite chainsaws will range from model to model but is usually between .2 mm to .35 mm. You can use a feeler gauge or a plastic shim to set this distance.
The magnets on the flywheel must be clean and show no signs of discoloration. Dirt and wear will cause a low magnetic field and the charge won’t develop properly. The magnets should be strong enough to pull a large socket to them. You can clean the flywheel with a wire brush and a rag; just wipe slowly and carefully so you don't damage the flywheel's fins.