Bad coil question

[kellyisu]

For those of you who have ever had a coil go bad on them on a 2 STROKE, I wanted to know what you motor sounded like when you were able to keep or get the motor to run with a bad coil?

Thank You

 

[mmf]

Re: Bad coil question

I have had coils go bad before that would not fire at all at idle, but fire good at high RPM. I have checked many of them over the years and noticed on most, that the high side resistance gradually changes before they quit. That's how I pick out coils from my parts junkpile when I need one, by measuring the high side resistance. For example, if I find 3 coils with say around 930 ohm reading then one with a reading of say 700 ohms, I will not use the 700 ohm coil and find another close to 930 ohms. Sometimes you just have a breakdown of the HV insulation inside the coil and it will "jump" fire inside the coil windings and make a weak spark or no spark at all...at least that's been my experience......note, the same thing happens to high voltage electric motor windings in industrial environments. The finer the wire, the more prone the winding is to the enamel insulation breakdown.

 

[mmf]

Re: Bad coil question

forgot to say, be aware that the coil resistance will have small differences in resistance at different temperatures! (cold versus hot)

I forgot to answer your main question too, yes some motors definately will run with a bad coil especially 4 or 6 cylinder engines.

 

[green4themoney]

Re: Bad coil question

i had a bad coil and it would run intermittenly on one cylinder (at idle) every time you would go to idle down it would die but you could bring it down slowly