Cooked Coils

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Stillreel

Stillreel

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My relatively new 12V coils are reading 4.4 ohms resistance in testing after difficult starts. Literature states 3.2 - 3.6 is optimum. Is 4.4 allowable error or have I cooked the coils? They are less then 4 years old.

Thanks

BC
 
The coil resistance only matters for type of ignition to tolerate pumping up voltage and back lash voltage spikes. We would need to know the un-used ohms to know if yours has increased towards impending doom. Hot to cold measures might give some clue. Do feel for coil heat on a run, should be just warmish to touch.

Otherwise order more and see what they read. Just measured my aftermarket coils on contact breaker ignition to get 1.7 and 3.5 ohm. Points can tolerate more variation than electronic ignition which tend to like the lower ohm coils. Apparently if bike fires up fine then good to go til it don't.
 
Thats the problem H; its not starting so good. Maybe the battery. I'm still measuring 12V but it is getting old (4 years). The problem is; do I buy new coils and try the old battery or the other way around. With my luck, I;ll end up having to buy both.
 
It looks like you will need a battery anyway. But going into the winter season, wait. Have you tried to throw it on the charger and start the bike with it connected?
 
Oh yeah definitely poor battery can do this as I've experienced on points or Boyer getting hard and harder to start till just wouldn't to discover battery measured ok til switch turned on. BTW unless idling around slow a lot then ya don't need to lug around but 4-6 ah battery.
 
New coils are cheap enough, I have bought quite a few recently as I have misdiagnosed a few misfire problems..
 
Coils are about $60 shipped a pair. Not bad for peace of mind. I replaced the coils on my combat recently. It ran fine, but died randomly. Funny, both of my Lucas coils were date stamped 9/72. Cheap Lucas crap :lol:
 
I got a pair of the Emgo 12V coils from MAP for about $60. They were OK until one of them quit quite unexpectedly. I took it apart and the wire came off either the - or + terminal inside. Forget which. I reconnected it and pressed it back together. Lucas is not the only crap. I bought a spare.

Dave
69S
 
Never forget that the coil clamps have a super low torque or you will crush the bodys and short out internals.The bodys are made out of muffin butter and uneaten leftover scons ,and teacup spoons.
 
Its Official . . .

Cooked Coils
 
That's a spoof emblem and can't be the real deal as its got a flame going, sheeze.
I've seen switches that say, off, dim, flicker, smoke, find me one and I'll snap it up this time. see the real deal below in box, taken after sun set of course.
 
Stillreel said:
My relatively new 12V coils are reading 4.4 ohms resistance in testing after difficult starts. Literature states 3.2 - 3.6 is optimum. Is 4.4 allowable error or have I cooked the coils? They are less then 4 years old.

Thanks

BC
Click to expand...
So are these stock coils? Are you running points or electronic ignition? Are they wired in parallel or series? Typically stock coils are 6 volt (17M6) wired in parallel with points and a ballast resistor for post '71 Commando.

For electronic ignition you want them wired in series and delete the ballast resistor. Or use the proper 12 volt dual output H-D coil.
 
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