1980 Johnson 2HP Service Manual, Page 27Get this manual
MAGNETO ignition system consists of flywheel type magneto connected to the spark plug through high tension leadmagneto is se1fcontained electrical generating unit consisting of an armature plate with one coil and lamination assembly, condenser, and breaker assernblypermanent magnet cast into the flywheel completes the assembly4 147
THEORY OF
magneto ernploys the interaction of the fast moving flywheel magnet and stationary to generate an electric current of voltage sufficient to across the spark plug air gapThis creates the spark that ignites the fuel in the cylinderignition coil actual1y consists of two coilsOne, cal1ed the primary, consists of relatively few turns of heavy gage copper wireother, cal1ed the secondary, consists of many turns of fine gage wirecoils separated insulation and mounted the center leg of an shaped laminated iron One end of both the primary and secondary coils is grounded to the other end of the primary connects to the insulated stationary breaker pointThe other end of the secondary connects to the spark plugThe coil and movable breaker point grounded to the armature plateWhen the poles of the flywheel rnagnet sweep past the first and center legs of the magnetic f10w is momentarily established in the temporarily assurnes direction through the from the north pole of the permanent rnagnet to its south poleAs the poles of the rnagnet sweep further along the in the center leg collapsesrapid development and collapse of in the cente leg induces an electric charge in the coilscurrent in the primary f10ws through the closed breaker points and sets magnetic of its own in the center leg of the direction of the mentarily opposes the establishment of reverse in the center leg as the poles of the f1ywheel magnet to the center and third leg of the At this precise rnoment, the breaker points opened the engine crankshaftThis interrupts the f10w of current in the primary, and the opposed in the center leg collapses