Ignition coil ohms, does it matter

[Sparky84]

Does it really matter what ohms rating your coils are, think 2.4 for 1100.

Hard to find spares that are 2.4
Found 3.5 and 4 ones that should fit in, just looking for spares.

Cheers
Alan

[red]

Does it really matter what ohms rating your coils are, think 2.4 for 1100.
Hard to find spares that are 2.4  Found 3.5 and 4 ones that should fit in, just looking for spares.
Cheers
Alan

Alan,

If there are Ohms specs in the FSM, I'd go by them.  Coils are just another name for inductors, and inductance is measured in Henries.  You won't find many Henry meters outside of an electronics repair shop, almost never in a bike shop.  The FSM does not provide a Henries values anyway, but the trick there is to measure a few new ignition coils, and go by those specs for Henries.  You will have one reading for Primary wiring, and one reading for Secondary.  As coils fail (often gradually, unless the case gets broken), the Henries (and Ohms) values of the ignition coil will decrease.  A lower than normal Ohms reading usually means a coil is getting close to failure. 
What does the FSM give as the good Ohms values for the Primary and Secondary windings?

[T Legg]

Does it really matter what ohms rating your coils are, think 2.4 for 1100.

Hard to find spares that are 2.4
Found 3.5 and 4 ones that should fit in, just looking for spares.

Cheers
Alan


    The 2.4 ohm coils will flow more current and make a bigger magnetic field so when it collapses it will make a hotter longer spark. If you use the higher ohm coils it shouldn't hurt your ignition parts but weaker spark.
   If you had an ignition module designed for higher ohm coils and used the low ohm coils it might be damaged by overheating due to the extra current flow .

[aviationfred]

The Dyna GREY coils are what you want for an aftermarket coil.

https://www.ebay.com/itm/Yamaha-FJ1200-All-Years-2-2ohm-Dyna-Coils-/292932229821?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l6249&mkrid=710-127635-2958-0

Brand new coils are still available from Yamaha. They are expensive, but you will have the piece of mind that they are the correct coils.

https://www.partzilla.com/catalog/yamaha/motorcycle/1985/fj1100n/electrical-2

Fred