Coil upgrade on XS1100F

[Lettuceman]

I am ready to install MikesXS black $32.00 coils on my bike. I understand the physical replacement, the Orange/R-W/Grey wiring, and the spark plug wiring.

I have reviewed the posts on this site but remain confused on the step to by-pass the resistor on the E/F model. This seems to be necessitated by the coil secondary circuit ohm difference. To by-pass the circuit I am assuming that one would simply disconnect the resistor R/W wires and jump them to eliminate its function. Is this correct?

PS – I am one of the quite users of this site, I read a lot of posts and relate them to my situations. I truly appreciate all who respond with good advice and useful experiences. Thank-you.

[bikerphil]

You are correct, just unplug the ballast and plug the two ends of the wiring harness together, and you're done.

[TopCatGr58]

What Phil said,

But the removal/bypass of the ballast resistor isn't for the ignition coils Secondary Resistance, but the Primary Resistance and voltage needs. The Mikes XS coils are 12 volt and ~3 ohm, the OEM 78 were 1.5 ohm, the BR is 1.5 ohm, total = 3 ohms.what the TCI needs to see. They(oem) are 12 volt coils, but once the engine is running, the power to them is routed THRU the BR for a resultant ~9 volts which prevented them from overheating and frying. The BR is bypassed by the TCI during startup to provide stronger starting spark, then routed THRU the BR during running, again, by the TCI.

Newer technology can handle and needs the 12 volts all the time, and already provide the required 3 ohms for the TCI NOT to fry, so bypassing the BR solves both situations, full 12 volts ALL the time and the proper 3 ohms for the TCI!
T.C.

[79XS11F]

When you say "Newer technology" does this mean that the BR should remain connected when using OEM coils?
Rob

[tw1980]

When you say "Newer technology" does this mean that the BR should remain connected when using OEM coils?
Rob

Yes if you have oem coils.Leave the resister connected. Terry

[clcorbin]

I currently have a set of Accel Super Coils installed (yellow). I have them wired through the ballast resistor. Does anyone know if I need to bypass the BR, or do I need to get off my lazy butt and take the DMM out to the bike and ohm them out myself??

[cywelchjr]

I currently have a set of Accel Super Coils installed (yellow). I have them wired through the ballast resistor. Does anyone know if I need to bypass the BR, or do I need to get off my lazy butt and take the DMM out to the bike and ohm them out myself??

I THINK all the aftermarket coils are 3 ohm, but you should check to be sure before bypassing the ballast resistor.

[crazy steve]

They(oem) are 12 volt coils, but once the engine is running, the power to them is routed THRU the BR for a resultant ~9 volts which prevented them from overheating and frying.

Actually, the voltage is dropped to 6 volts; with two equal resistances in series, the voltage drop across each will be the same amount. If you're seeing a different amount on your meter, either the meter is wrong or you're seeing the effects of inductance.

'78E original owner

[cywelchjr]

Actually, the voltage is dropped to 6 volts; with two equal resistances in series, the voltage drop across each will be the same amount. If you're seeing a different amount on your meter, either the meter is wrong or you're seeing the effects of inductance.

'78E original owner

Inductance will affect the resistance, increasing the resistance of the coil while pulses are happening. So, while the DC resistance is indeed 1.5 ohm, the ac resistance (otherwise known as impendence) is higher, resulting in an imbalance, which of course I'm sure that the engineers took into account.

[Rasputin]

I currently have a set of Accel Super Coils installed (yellow). I have them wired through the ballast resistor. Does anyone know if I need to bypass the BR, or do I need to get off my lazy butt and take the DMM out to the bike and ohm them out myself??

Yes the Accel Super coils that will go on a 79F will require you to bypass the ballast resistor. The 140403 coils have the 3 Ohm resistance. The others that are the 140404's are the CDI type and have only .7 ohms resistance. You have 12 volts to the coil on a 79 which calls for the 140403 inductive type. So yes you should bypass the BR.

[clcorbin]

Thanks. I went out and ohmed out one coil and it came out right at 4 ohms. The bike has been running fine with the ballast resistor inline, but I bet it will make more power and get better fuel economy when I get rid of that ballast resistor.

[clcorbin]

Well that was easy. It took longer to find the correct socket to unbolt the ballast resistor than it did to bypass the thing.

[bikerphil]

I bet it will make more power and get better fuel economy when I get rid of that ballast resistor.

Had this issue with my 79SF. The PO installed Accel yellow supercoils and left the ballast in line. It ran fine that way. After I removed the resistor, there definitely was a noticeable increase of pep and power with the higher voltage running to the coils.

[Lettuceman]

Thanks for everyone's thoughts. It was not the coils and I am now back into the carburetor.

[DiverRay]

If you get stuck, give me a call. I'm about 40 minutes from you, and may be able to help. Ed and I could probably ride out on Sunday afternoon, help a little, and stop for a bit of liquid.
But seriously, IF you are stuck, send a pm and I'll see what I can do with my schedule. As I have a few of these, I know how and where too look.
One thing I DID learn about the resistor bypass. BE SURE TO USE SOMETHING TO KEEP IT FROM SHORTING OUT!! I was left stranded because one connector shorted against the fuel tank. Wrap the connectors well in tape, or use heat shrink tube on them!