Can I use this spark tester in cdi?

[jitterbug127]

This is my personal/keeper motor. I have a 1990 15 hp Johnson that was running great and randomly quit today. I’ve done a bunch of work to the motor in the last few months so I’m a little surprised to say the least. I’d like to start with the basics and make sure I’ve got spark. I bought a new spark checker recently and wanted to make sure it was ok to use with cdi? I’ve only tested spark with this one on points/magneto motors.

Thanks!

 

[brodmann]

Absolutely you can.

 

[jitterbug127]

Checked the spark, looked great, gave her a few more pills fired right up. I’ll get her out and run her good this week.

 

[brodmann]

What did you set the gap at? 3/8" or even 7/16" is a good indication of a strong spark.

 

[Nordin]

When checking spark on a CDI ignition system with that kind of tester you have to ground out the cylinders that you do not test at the moment.
If not, you can damage the CDI box as it have no way to dump the voltage in the capacitors when it have to.

 

[jitterbug127]

What did you set the gap at? 3/8" or even 7/16" is a good indication of a strong spark.

It jumped a 1/4 well.

 

[jitterbug127]

When checking spark on a CDI ignition system with that kind of tester you have to ground out the cylinders that you do not test at the moment.
If not, you can damage the CDI box as it have no way to dump the voltage in the capacitors when it have to.

How would you suggest grounding out the other cylinder? Testing both coils at the same time with 2 of the same tester or doing something else? New information for me.

 

[Nordin]

If you have two of those spark tester then it is okey (BTW there are multipel cylinder spark tester in the market), BUT if you have only one you have to ground the other cylinder (two cylinder engine).
There are two alternative, have the spark plug connected to the HT wire boot and ground out the spark plug or put a steel rod or similar in the HT wire boot and connect the rod to ground.
The important thing is to have the not testing cylinders HT wires connected to ground.

 

[racerone]

Are you sure that ignition will be damaged on this motor, by testing one cylinder at a time ??

 

[jitterbug127]

Are you sure that ignition will be damaged on this motor, by testing one cylinder at a time ??

I am not sure. i posted the question to find out if it would be ok or not.

 

[Nordin]

It may not be able to broke but why take a chance.
To ground the other cylinder is an easy fix.