Ask the Editors: Weak Spark Diagnosis
Weak, yellow spark from a fouled plug.
Have you ever heard the old mechanics adage KISS? That stands for Keep It Simple, Stupid. That may sound harsh but it is a lesson for us all that when it comes to diagnosing a malady, it is always wise to start at the simplest problem and work your way up to the most complex.
Weak spark can be caused by a wide variety of culprits. In the KISS school of thought, the simplest to replace would be the spark plug and the wire. A worn or dirty plug and/ or worn insulation or broken contact within the wire will cause what you are experiencing without fail. Plus, if you replace these relatively inexpensive items and the problem still persists, you gave your quad a tune-up and now have functioning extras of these items on hand.
From there we have to move our investigation backward along the ignition tract. Testing your coil is a pretty straightforward process. Grab an electrical multimeter and set it to Resistance (Ohms), locate the machine’s coil and begin testing the continuity of the coil packs. Here is a very easy to follow video on the subject that will guide you through the step by step.
By sheer process of elimination and some help from the KISS methodology, if your coil checks out, you have a fresh plug and wire but you’re still not getting adequate spark, your culprit is likely the CDI box.
