How to Test a Motorcycle Ignition Coil

Testing a motorcycle ignition coil is important especially when you install a new motorcycle ignition switch. Electrical problems on a motorcycle can also occur so testing will help determine these problems. 2 gadgets can help you test these problems. The ohmmeter, also known as a multimeter, sends out a very low powered electric charge through a wire and measure how much resistance there is in the wire to the charge going through it and is measured in ohms. The amount of resistance you will set the ohmmeter depends on what you are testing. An information manual for all types of resistance for specific testing is usually available in an automotive shop and can be very useful in other things wire settings not just for vehicles but most appliances inside the home.

Step 1 – Charge the Battery

Fully charge your motorcycle battery. This will ensure the accuracy of testing your ignition coils. If you battery is not fully charged, it will be hard to determine if your ignition coil is the problem or simply just a dead or weak battery.

Step 2 – Open the House of the Coils

Access the wiring for your ignition coils by opening the housing of your ignition coils. There are times that ignition coils can be located right under the flywheel and be self contained, meaning the ignition coil and ignition starter coil are one in the same. Mopeds and small European bikes have these types if ignition coils.

Step 3 – Remove the Plug Cap                    

Remove the plug cap off for the test. This can affect the accuracy of your test because cap itself can add 300 ohms resistance to your results making it very inaccurate.

Step 4 – Get the Resistance

Measure resistance between low-tension wire and ground terminal wire. The low tension wire is also called the primary wire. The result should be very low around .5 to 1.5 Ohms. If you ware not sure about which one the primary wire is, it is the small wire going towards the CDI box or CDI points.  Measure resistance between the high tension wire and ground wire. High tension wires are also known as the secondary wires. The result should be high around 6000 to 13000 ohms.

Step 5 - Study the Results

If the resistance between these wires is outside these base numbers then the ignition coil can be bad. There are times that an ignition coil will work fine when the engine is cool but starts to foil when it is starting to warm up. If you are willing to spend a little more, there are machines that can test these ignition coils under pressure.

Step 6 – Test the Coil

Another simple test you may do regardless of type of coil is to check the voltage going to the coil with battery connected. If you have a 12V DC system and you are getting close to 12vdc at the coil terminal and no reading is coming out of from touching the coil you either have a bad connection or bad coil.