An opposed-piston engine optionally contains an ignition system that is at least partially contained within the combustion chamber to enhance the combustion efficiency of a fuel-air mixture within the combustion system. More specifically, the ignition system contains at least one spark plug having an elongated center electrical delivery electrode, and, an elongated ground electrode. Accordingly, the elongated electrodes extend from an area adjacent to the inner periphery of the cylinder to a radially central area within the combustion chamber. Yet further, a cooling jacket is incorporated to provide cooling of the spark plug.

A magneto timing control system is described. The magneto timing control system can include an element configured to adjust tension of one of a first section of a belt and a section of the belt, wherein the belt is in communication with at least one magneto. The tension of the first section of the belt and the second section of the belt control a timing advance and a timing retard of the at least one magneto.

In an ignition device, a proportion of a yoke end width defined as a distance from one end to another end of an end portion of each of a pair of yokes in the circumferential direction to a magnet width defined as a distance from one end to another end of a permanent magnet disposed on the outer circumferential surface of a flywheel, in the circumferential direction is in a range of 60% to 100%. Moreover, a proportion of the magnet width to a yoke interval between the pair of yokes is in a range of 95% to 100%.

An ignition coil unit is attached to an engine body. The engine body includes a cylinder head having a plug hole and a head cover that covers the cylinder head by including an opening hole facing the plug hole. The ignition coil unit includes a coil unit that generates a high voltage and a cylindrical coupling unit that connects the coil unit with a spark plug. The coupling unit includes a flexible sealing section fitting to an outer peripheral surface of the high tension tower and a harder joint fitting to a tip of the sealing section. The sealing section includes an adhesion portion to tightly contact the head cover and a neck portion at least between the adhesion portion and the joint in a Z-axis direction. The neck portion is formed by partially constricting an outer peripheral surface of the sealing section radially inside.

A handheld engine-driven working machine comprises an internal combustion engine and an ignition control device; wherein the ignition control device can switch its control between a normal mode and a operation mode, wherein during the operation mode, the ignition timing within the high speed range is maintained at a second BTDC angle, and the ignition timing within the medium speed range is advanced more than a third BTDC angle between a first BTDC angle and the second BTDC angle, and wherein at any rotational speed within the medium speed range, the ignition timing during the operation mode is advanced more than the ignition timing during the normal mode.

A magneto timing control system is described. The magneto timing control system can include an element configured to adjust tension of one of a first section of a belt and a section of the belt, wherein the belt is in communication with at least one magneto. The tension of the first section of the belt and the second section of the belt control a timing advance and a timing retard of the at least one magneto.

Provided is an engine knocking detection apparatus capable of reasonably implementing necessary measures for water and dust proofing and against breaking of a cable, and the like at low cost as well as precisely detecting and effectively suppressing or avoiding knocking while suppressing cost and weight increases as much as possible. The engine knocking detection apparatus is adapted to detect knocking in an engine that adopts a flywheel magneto ignition system with an ignition coil unit securely attached to a cylinder, the ignition coil unit including an iron core, a coil wound around the iron core, and a control circuit board attached to the coil, and has an accelerometer for knocking detection attached to the iron core of the ignition coil unit.

An ignition device for an internal combustion engine is provided which improves ignition while reducing electric power consumption. An ignition device for an internal combustion engine includes an ignition plug that is placed with a tip exposed on an end in an axial direction of a combustion chamber formed in a cylinder and that includes a central electrode and a grounding electrode provided opposing each other at the tip, and a magnetic field former that forms a magnetic field in a direction in which a magnetic field vector substantially vertically passes through an approximate two-dimensional plane including a spark discharge path formed, by a gas flow ejected to the end in the axial direction of the combustion chamber, between the central electrode and the grounding electrode, and extending in an approximate U shape in a direction orthogonal to the opposing direction of the electrodes.

A multiple-keyed crankshaft and flywheel provides for different ignition timing options for an internal combustion engine. The crankshaft of the engine includes multiple keyways set at designated angular displacements of the crankshaft that correspond with keyways on a flywheel for providing different timing options for the engine. The flywheel may be mounted to the crankshaft by aligning one of the keyways of the flywheel to one of the keyways of the crankshaft related to a particular ignition timing selection.

A multiple-keyed crankshaft and flywheel provides for different ignition timing options for an internal combustion engine. The crankshaft of the engine includes multiple keyways set at designated angular displacements of the crankshaft that correspond with keyways on a flywheel for providing different timing options for the engine. The flywheel may be mounted to the crankshaft by aligning one of the keyways of the flywheel to one of the keyways of the crankshaft related to a particular ignition timing selection.