Small Engine Help – Small Engine Help everyone can understand

The 2 Types of Small Engine Ignition Systems: Small Engines ignition systems have advanced with changes in technology but their purpose of “delivering the spark” at the precise moment has remained unchanged. As a small engine repair person you’ll come across the two types that have been on the market for the past century. A professional small engine repair person knows the ins and outs of both systems because they're sure to come across either one in their journeys of small engine repair. The two types of small engine Ignition systems: Solid-state systems: the more modern option, these systems use a tiny transistor in the coil or armature to close the electrical circuit that travels through the spark plug lead to the spark plug(s). Breaker point systems: used on engines made before 1980, these systems use a mechanical switch instead of a transistor to close the electrical circuit used to produce a spark. If you regularly work on small engines as a small engine mechanic, you will appreciate both systems and have a need for knowing how they both work and how to diagnose them. Most modern consumers however, will never come across the older breaker points system as they nowadays only appear in older antiquated small engine powered equipment that is becoming less and less common. Can’t say I miss the old breaker points ignition system as they had many more potential for not delivering the spark then today's modern mostly trouble free solid state ignition system. The common issues associated with today's modern small engine solid state ignition system: spark plug going bad The ignition coil intermittently or fully fails to deliver a spark to the spark plug. The most common failing of the solid state ignition coil on a modern small engine is whereby the insulating coiling on the coils windings degrade to the point that the heat generated from the engine running heats up the coils windings its losing spark intermittently or fully from the condition caused as a result of this normal engine heat. In this case, the solution is to replace the ignition coil. Diagnosing Tips of todays small engine solid state ignition system: Disconnect the ignition kill wire from the ignition coil to determine if your fail point is related to the safety and ignition circuit from the piece of equipment the small engine is powering. Removing the spark plug from the engine, leaving it connected to the ignition spark plug wire and turning/cranking the engine to see if the spark plug is throwing a normal blue spark across its electrode gap. (it's possible to have a weak orange spark which when subjected to the engines compression cycle would not be sparking and engine would not start. This condition might be a fouled spark plug or a bad ignition coil.) The older breaker point system used before 1980, is becoming less and less common as older engines using that system are fading into obscurity as they are being recycled. None of us are sad to see them being phased out because they had several moving parts that could wear out and needed cleaning and adjusting whenever the engine put in significant hours of use. These older systems featured mechanical opening and closing points that were pushed open by a plunger from a cam on the crankshaft. The points themselves could burn or get bad contacting surfaces so you had to clean these contact points and readjust their gap. You also had to get at this ignition system behind the flywheel of the engine which was significantly more work then the more modern solid state ignition system that doesn’t have any moving parts or regular maintenance besides changing the spark plug. Diagnosing Tips of older small engine breaker points ignition system: Check if the positive + wire going to your ignition magneto coil receives 12v DC power from the battery of the equipment this engine is powering. Check if the magneto ignition coil has proper grounding to the engine or base of engine. Check the wire going from the magneto ignition coil to the breaker points. Make sure it's not shorting out anywhere and has proper connection on both ends of termination. Removing the spark plug from the engine, leaving it connected to the ignition spark plug wire and turning/cranking the engine to see if the spark plug is throwing a normal blue spark across its electrode gap. (it's possible to have a weak orange spark which when subjected to the engines compression cycle would not be sparking and engine would not start. This condition might be a fouled spark plug or a bad magneto ignition coil.) Check the breaker points contacts for misalignment and burned contacts surfaces. In this case you may realign them, clean the contact points with a small piece of sandpaper then set their proper specced gap with a feeler gauge. The small cylindrical shaped condenser used on this breaker points ignition system may also be the reason you are not getting the spark to jump the spark plug electrode gap. The role of this condenser is to store up enough to jump the gap when the opening and closing of the breaker points asks for the condenser to release its charge and the charge creates a spark to jump across the spark plug's electrode gap. Check the spark plug wire for cracks in the wire and/or end terminal connection rubber boots. Cracked rubber boots or in the wire itself would let the spark short out or jump the gap to the engine and not deliver a spark at the spark plug electrode. Lastly, the most unlikely but still possible reason for not having ignition spark on a small engine, may be the flywheel magnet(s) being weak. I have actually run across this on a brand new, never used Honda clone, non-branded 212cc engine on a powered cement trowel. This piece of equipment came from a Ritchie Bros auction and had never been used. We unpackaged it, and it would not start. I had a seized 5hp Honda engine to swap parts from. After swapping the ignition coil from the Honda not making this no-name engine not have spark, I decided to check the magnet with a flat screwdriver. It didn’t have nearly the same magnetic pull the original rusty Honda flywheel had when testing with my flat screwdriver touching the magnet. So I swapped flywheels from the seized 5hp Honda to the new Chinese made Honda clone engine. Lo and behold, now it had spark! I could not believe it! I had never ever come across this issue in all my years repairing small engines but I was impressed that I had figured it out. As rare as this is, it is a possibility. These older breaker points ignition systems took various forms across the industry in their time. Depending on the manufacturer, some were extremely unhandy to adjust and work on being they were typically located and tucked away behind the flywheel of the engine. I’m not aware of any such systems that were not housed behind the flywheel. Most of us small engine techies are glad to not come across an engine with such a system, but when we do, we know what to do with them.

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