Coil heat

[koko64]

At what temp do you become concerned about coils overheating? Or what is an acceptable Operating temp of a coil before heat saturation and component failure? I've seen coils that were mismatched with other ignition components overheat and even emit lightning (on a BSA '66 Lightning)!
Coils can run warm to the touch without issue. On Kokusan ignition models the 3ohm coils seem to run a bit hotter than the 5 ohm . What's your anecdotal data?

I'm testing second gen CCW coils with correct resistance plug caps, oem wires and plugs but the coils are quite warm to the touch without being hot if you get my drift.  I know the Ignitech ignition can be quite hard on 3 and 5 ohm coils but this bike (an M600) has stock Kokusan ignition. I have ensured that the coils are not earthed to the frame as per Chris K's instructions as this can cause issues. The stock coils had earth wires to the coil posts so I removed them. Is this a factor?
Cheers.

[Howie]

I would guess there would be no specific any coil temperature, but some can get too hot to touch.  Back when we used to test run the students worked on we would feed them 12 volts direct, no resistor.  Of course, sometimes they cranked a long time.  Coil failures were rare, and usually due to the oil boiling.  Boom goes the coil

I have no ideas about Chris's instructions.

[Frank C]

Coming from a different industry...but most manufacturers of rotary and linear motors state a max winding temperature of 125 to 155 C.  Anything higher and the "stuff" they use to isolate the windings starts to reflow, causing a short.

Assuming an ignition coil would have similar issues.

[koko64]

That's interesting info. Makes sense. Cheers.