What can contribute to coils going bad?

[Guest]

Working on getting the '93 GS500E back on the road.Long story short, got everything back together, still running on one cylinder.

Ohm out the signal generator, in spec.

Ohm out left coil primary and secondary resistance, in spec.

Right coil primary resis., spec.

Right coil secondary resistance, value is high. The manual says it should be between 18-30k, it's a little above 98k. Pulled the wire, infinite resistance. Replaced plug wire with new, checked coil secondary resis., still above 98k. Pulled plug wire completely, checked resistance at plug wire output terminal, same result.

Okay, so the coil's bad, , have replacements on the way.

What I'd like to know is what things can contribute to a bad coil? I figure it would be better to find a culprit (if there is one) while I'm waiting for the replacement coils to arrive so I don't destroy the new ones when I install them.

Oh, one other thing--my manual (Clymer) states:

The igniter unit can only be tested with the Suzuki Digital Igniter Checker (part No. 09931-64411). This is a very expensive piece of test equipment and requires a thorough working knowledge of its use.

Is this true, or is there a way to check out the igniter without the "Suzuki Digital Igniter Checker"?

[Hap Call]

I can't address the Suzuki Digital Igniter Checker, but I can talk about the coil issue. Depending on the type of insulation used in a coil, over a period of time the insulation will begin to deteriorate due to heat and actual flexing of the windings due to harmonics. The harmonics can also contribute to the actual winding becoming open, kind of like when you flex a wire coat hanger until it breaks. There are other reasons such as manufacturing defects and material defects that can contribute to the early demise of a coil.

If your coils lasted 17 years you are doing okay and there is probably no external issue causing the failure.

Hap

[Sparky]

check cliffs site, there are tests for the ignitor