Motorcycle Repair: Coils, spark plug gap, resistance test

Question
Can you explain to me how to test ignition coils for a 1982 Yamaha 750 Maxum.  

Answer
Hi Dan.

There are 2 types of test for the ignition coils, the dynamic test and the resistance test.  Before you do either of them, make sure that there are no shorts in the ignition circuit.

For the dynamic test, pull the spark plug and reconnect a new or known good plug to the coil just as if the plug was installed on the bike.
 Place the plug base somewhere that will give it a good ground, like against the head, so that you can see the electrode and spark plug gap.
 Push the starter button and look for a fat, blue spark as the bike turns over.
 Repeat with each suspect coil.

If the plug is not a known good plug, then the results will be inaccurate.

The second test is the resistance test.
 To do the resistance test, you need the repair manual for your bike because the test proceedures will vary pretty dramatically from bike to bike and year to year.

Good luck and ride safe.
FALCON