Coils

[XS1100_OEM4ME]

OK, not a rocket scientist here but, I have OEM coils, my understanding of coils is two windings of wire around a conductor in a heat sink of some kind? One is a charge coil, small # of windings, the other is a discharge coil, large # of windings. So, my question is, if both windings are intact, how is the efficiently changed Is it more the grounding, or old ign wire's, or what. I don't want to spend $$$ now, but would rather get my current OEM coils working up to standard, any thoughts

[Lonerider62]

I found this site today when I was trying to get some better info on why we see different types of coils and ignitions. It's on the long side but a good read that will enlighten most people on how our ignitions, and others, work and why.

http://www.gofastforless.com/ignition/howig.htm

[natemoen]

The usual problem is that the insulate separating the two coils degrades and then the two sides of the coil short out internally. Or the wires degrade and the circuit opens and current no longer passes through the wires.

Other than cleaning up all the connections before thw coils and putting new plug wires in there is nothing else you can do except replace the coil.

[crazy steve]

You can also have issues with the spark plug wires' connection internally on the coil, as well as bad wires. Some guys have had success replacing the wires, but it's a bit of a PITA.... look here: http://www.xs11.com/forum/showthread.php?t=137

This isn't something I would recommend, but it is a possibility. But as Nate said, if the coils are failing, the coil is toast....

[XS1100_OEM4ME]

So

So, if I have this right, it is the internal coil of wires that lose there insulation and short inside the windings that cause the breakdown of output i would guess over heating would cause this over time Mine both work, but I have seen two plugs on one coil seem to foul quicker then the other two. I will break down and buy new coils and wires soon, just hate to keep throughing $$$ at it, I didn't care when they $$ seemed to grow on trees

[crazy steve]

There's a number of things that can cause reduced output; yes, if the primary and/or secondary coils internal to the coil start to go bad, that will cause reduced output. That's easy enough to check; simply put an ohmmeter across the two windings and see if they meet spec. The primary windings should check between 1.35 and 1.65 ohm, the secondary should be 12-18K ohms; above or below these numbers means a failing coil. It is important to check the secondary winding with the spark plug ends removed; those ends are supposed to be 5K ohms each (+/- 10%). These simply unscrew off the wires, and are known for poor connections where they screw in. If any ends check out of spec, replace them; they're cheap enough at about $3-5 each. With the ends installed, you should see no more than about 29K ohms across the two plug wires.

[XS1100_OEM4ME]

plug ends

Yea, I have all new ends, NGK 5 ohms, did the 1/4" clip on the wires. The bike runs OK, some poping, not much now that I turned the mix screws out 1/4 turn (thanks Phil on both the mix screws and plug caps) I just have two plugs that foul quicker then the other two 32 year old coils / wires $$$$ in my future, not much else I haven't replaced

There's a number of things that can cause reduced output; yes, if the primary and/or secondary coils internal to the coil start to go bad, that will cause reduced output. That's easy enough to check; simply put an ohmmeter across the two windings and see if they meet spec. The primary windings should check between 1.35 and 1.65 ohm, the secondary should be 12-18K ohms; above or below these numbers means a failing coil. It is important to check the secondary winding with the spark plug ends removed; those ends are supposed to be 5K ohms each (+/- 10%). These simply unscrew off the wires, and are known for poor connections where they screw in. If any ends check out of spec, replace them; they're cheap enough at about $3-5 each. With the ends installed, you should see no more than about 29K ohms across the two plug wires.

[bikerphil]

I just have two plugs that foul quicker then the other two

2 and 3 by any chance?

[XS1100_OEM4ME]

2 and 3

Yes it is, have an idea

2 and 3 by any chance?

[bikerphil]

Those 79 Special carbs have "richer" emulsion tubes (less air mixture holes) in the center two carbs to try to keep those cylinders cooler. Just thinking maybe that's why the plugs look darker.

[XS1100_OEM4ME]

Thanks

Thanks, I did not know that I am not sure I put them back in the right carbs as I soaked them all over night in one container, then reinstalled everything, thinking they were all the same, I will check the next rebuild

Those 79 Special carbs have "richer" emulsion tubes (less air mixture holes) in the center two carbs to try to keep those cylinders cooler. Just thinking maybe that's why the plugs look darker.