1. Place the Spark Plug into tester hole 1 or 2; If you want to compare the new spark plug and old one, place new spark plug into hole 1 and the old on into hole 2
2.Connect to power supply
3.Turn the key switch 4 clockwise to turn on tester, indicator 3 will light up, tester is now working at 1000rpm/min.
4. Again turn the key switch 4 clockwise,you can adjust the working frequency between 1000rpm to 6000rpm/min.
The higher the frequency, the stronger the spark strength.