Coil Readings

Had a coil fail on my KZ1300 on Saturday.
The coil which feeds 2 and 5 is not providing any spark at all to the plugs, but it is recieveing a perfectly good feed from the harness.
I swapped one of the other 2 coils just to be sure it is not another issue elswhere, and the other coil works perfectly on 2 and 5 wiring, so it has been a bad coil.

However.............when I carry out the 2 readings on my Multi Tester as shown in the K manual..........the readings are both 100% spot on and the same as the other 2 good coils.
To make things even more unusual..........I had another old coil from years ago which I now is not working and that shows all the wrong readings as you would expect.

Has anyone had this issue before when testing bad coils ??

Pete F
UK

Hi Pete, you have measured the coil resistance with direct current (DC) multi meter to determine the value of the primary and secondary coil winding? i presume yes. So in that case the coil resistance will be nominal or within the margin, showing it as good. However the same coil, when tested in condition in which is normally being used, (pulses from the igniter) it will fail to produce the spark, (i have experienced this while testing new ignition units for my kawa). Whats more if you are to put the spark plug under pressure it will be even more difficult for the spark to jump between electrodes due to higher resistance of the gas between theme, so spark in the air is not necessarily a good one in the combustion chamber under pressure. In my opinion to verify the coil function properly coil must be tested the way the table K26 page 241 of the Z13 manual is showing. I hope this help
Daro.

Wonder if it's breaking down with heat Pete, I had that with the original coils on my 13 & they measured OK when cold. Might be worth sticking it in the oven on a very low heat & taking the readings then.

Are you measuring resistance of the coil? A lot of ohm meters (especially cheap ones) can't accurately measure low resistance values, i.e. a few ohms, as the 'error' range of the meter is larger than the value being measured.

Thank you for your replies.................I am measuring my coils with my own very good meter which I have used on many other coils for other bikes as well as a 1300 and always had the correct results over the years..............

I agree with Phil here and think it is definitely related to temperature, as the coils do give a correct reading when cold, but obviously dont spark.

Peter F
UK