Quote Originally Posted by scout-j-m View Post
Yeah those are handy, I have one as well. I typically first use the adjustable air gap testers that you run to ground to make sure the spark is super strong when you turn the motor over. Then I will use the tester you linked while running the motor to see if the spark drops off or stays consistent while running. Only complaint with mine is it's impossible to see unless in low light conditions.
That was my problem with my older testers, but this one is insanely bright in full sun. Lisle did a good job on this one, shows rate and quality quite well. It tipped me to a coil getting weak on a Kawasaki Twin on my riding mower that was still running pretty good, but it had one spark plug that never looked as good as the other. I cleaned and swapped the plugs around, and "Ah HA!". Wires ohm'd out, new coil did the trick! Mower now runs with more power, fer sure!