13-06-16, 10:26 PM
When measuring the secondary, take the plug cap off and touch the probe direct to the copper core of the HT cable. The cap can be checked separately.
However, a multimeter is only of limited use for checking coils. An open circuit will show up OK as will a serious short, but quite often a coil will develop a short between two adjacent turns. The change in resistance is miniscule leaving the total well within specification, but it'll kill the spark.
A more reliable way of checking the spark is to take an old plug with the gap opened a few millimetres, stick it into the cap and thumb the starter while holding the plug against an engine fin. Provided you're not in bright sunlight you should see a healthy spark.
However, a multimeter is only of limited use for checking coils. An open circuit will show up OK as will a serious short, but quite often a coil will develop a short between two adjacent turns. The change in resistance is miniscule leaving the total well within specification, but it'll kill the spark.
A more reliable way of checking the spark is to take an old plug with the gap opened a few millimetres, stick it into the cap and thumb the starter while holding the plug against an engine fin. Provided you're not in bright sunlight you should see a healthy spark.