How do you test a moped coil?

In order to test a moped coil you need to use an ohmmeter. First you test the primary coil by touching the leads (2 wires with points on the ends that come off the ohmmeter) to the positive and negative terminals on the coil. The spot for the spark plug wire is not a terminal used for testing the primary coil. If your coil only has one terminal, other than the one for the spark plug, then the mounting hole is the other terminal. When you put the ohmmeter across these two points your reading should be less than 3 ohms. If the primary windings in the coil are fried, this reading is normally really high. The most common problem is the secondary windings. After testing the primary, you then need to test the secondary windings. To do this you touch one lead off your ohmmeter to the spark plug terminal and the other to one of the primary terminals. Your reading should be right around 10,000 ohms. It will most likely read 10K. It does not matter which primary terminal you use. It also does not matter which lead you use where. (When testing ohms the red and black leads are identical and the colors are not a factor.)