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Welcome to Myrons Wiring Diagrams Gallery. Mopeds have strange electrical wiring. Many have “secret” wires that must be grounded to run. Many have switches that normally would turn off something, but instead they turn on something (brake light or horn). Most of the wiring diagrams explain this, when it applies. This “secret wire that must be grounded to run” system is only on most 1970′s and 1980′s US models. The reason for this craziness is that European mopeds do not need brake lights, but US ones do. So many kinds power the brake light from the back side of the ignition source coil. One kind, Puch 77-later, 6-wire, powers the horn from the back side of the ignition source coil. So on a 77-on Puch, if you unplug the horn and push the horn button, the engine dies. Besides loosing spark, older mopeds also often burn out light bulbs. That is because a magneto generator alone, without a battery or regulator, ranges from dim lights at idle, to bright at full speed. So your bulbs are either too dim, or else they burn out a lot.
Modern (1990-later) mopeds don’t have the old moped wiring problems. They run a more powerful magneto, 70-80 watts instead of 30-40. All the lights run off one wire, with a 12VAC voltage regulator. To keep the voltage below about 13V, the regulator passes any excess current into the frame where it’s mounted. So when most of the lights are off, the frame is being warmed a lttle. This “regulation by wasting” system is common on motorcycles but not automobiles. Also nothing that the lights do ever matters to the ignition. Magneto ignitions after about 1993 are CDI (Capicitor Discharge Ignition) instead of points. They’re also maintainence free and have easier starting.
Many dozens more wiring diagrams will be added to the gallery soon. Eventually “all” US-model known mopeds will have a wiring diagram. Colorized and enhanced with notes is yet an even higher goal.
The Magneto Wires Chart above is like a master key that unlocks a lot of different mopeds. Knowing the color and function of the magneto wires allows a moped engine to be “hot-wired” to run without any of the bikes wires. (The chart will eventually include flywheel threads for pullers, and more models: Trac, Kreidler, Vespa and others.)
“Hot wiring” is the same as making an engine run, say on a work bench, completely separate and disconnected from the bike. Certain magneto wires matter, and must go to certain places. Other magneto wires are for lights only. The ignition wire must always go from the magneto (points, condenser, and source coil) to the spark coil, and not also to ground. The ignition ground wire must always go from the magneto (source coil ground) to ground. You can make this happen easiest with alligator clips on the ends of wires, like little jumper cables, called clip leads. To make any moped motor run on a work bench, you need some clip leads, a spark coil, a good spark plug, and the knowledge of what each magneto wire does. For example, on most Puchs, blue is ignition, and blue/black is ignition ground. On a Garelli, black is ignition and blue is ignition ground. On a Derbi, green is ignition and blue is ignition ground. Sometimes the wire colors are faded to grey, dark brown, or black. Then slice some skin off with a sharp knife to expose the true color inside.
