Coil Mod Info?

Did the coil mod yesterday, followed instructions to a T. Two questions... #1. before I started I checked volts at battery and at coils. I got 11.5 at battery (headlight stays on) and 8.8 at coils. Ok, really needed this mod. After I was done I checked again. I got 11.5 at battery and 10.5 at coils. It was quite an improvement but the question is... I'm still 1 volt less at coils than battery. Is this normal?, should it be the same as battery?, or did the mod do as advertised by going from 8.8 to 10.5 at coils? Doesn't seem to run much different but then I do have a strong ignition system (Accel coils, Dyna S) Plug condition will tell. #2 question, I kinda screwed up and mounted relay and wiring behind "left" side cover instead of "right" cover which has much more room. As you can see by the picture, will I have a problem with wires and fuse holder running under and then up left side of rectifier? (not sure what it's called) Does it get hot enough that I should move coil mod harness to other side of bike? A little long winded I know, thanks guys.

Post edited by: Bluemeanie, at: 2007/04/15 13:50

The Dyna S uses a lot of power (through the coils) so any drop will be made more pronounced by the S. But if the mod is done right, there should be very little drop in voltage. 1 volt is too much. You should try to isolate exactly where the drop is occurring in the path.

The Dyna S is good at masking the problem by using a large dwell to make up for the voltage drop, so It's possible the relay-mod won't show a large difference in performance over the DynaS alone. But it is still needed to prevent blowing fuses etc because the Dyna uses that extra current.

Just to be sure, you are measuring the voltage at the coils on the wire feeding the coils, not the wire going from the coils to the Dyna unit, correct ?

Yes, I measured right at the coils where the wires bolt on. I'm also getting the same reading at the output side of the relay (used) Could the used relay cause that? Just a basic relay, should I get a "better" one? What do you think about the wires and fuse holder near the hot rectifier? Thanks

If the input to the relay contacts is higher voltage than the output from the relay contacts, then the relay contacts could be bad.

Unless the contacts inside the relay are actually dirty (was it used?) one relay should be as good as another. Not sure why you are seeing such a drop. I just did the mod myself and I noticed about .5 volt drop. Some of that could be the length of wire and wire size maybe? Just for grins you could try say a 12ga. wire from the relay to the coils and see if it's any different. As far as the wiring near the rectifier I don't think it's a problem, but you could put some split loom on it to be safe, never a bad idea anyway. I found some nice blue split loom at advanced auto parts, but they only had one size it should be much smaller!

Thanks Loudhvx, pretty simple check. Will do so. And I think I need to move the system to the other side as another post mentioned that the rectifier does get very hot.

Poor battery health can cause ignition problems for sure. At 11.5 VDC, even with the headlight on, I would buy a small hydrometer and test the cells on your battery. Have you tested your reg/rec? It is easy enough. Start the bike and check voltage at the battery terminals using a multimeter. At idle you really should have over 12VDC... ~12.5 VDC. Rev engine to 4K rpm. At that engine speed, you should have ~14.5 VDC. That is a decent check of the charging system. If the battery cells are not marginal and you have good voltages when the bike is running at idle and 4K rpm, then I would pull all the connectors and clean them and use some dielectic grease on them... especially those that had to do with the charging stuff... reg/rec and main fuse wires. I honestly don't have a good sense of the heat issue from the reg/rec on a relay. My reg/rec units are nowhere near the relays on my bikes.