Dual Coil for my Honda?

georelle · Posted: June 9, 2009, 9:01 am Post subject: Dual Coil for my Honda?

I have acquired a 78 Honda CM 185T. It does not have a coil and they are nearly impossible to find. The CM 185T is a 6 volt twin cylinder single point bike. It had a dual coil on it. I was checking out the dual coils MikesXS has. I am thinking the one with the 4.5 ohm primary(17-6822) might do the job. I don't think there should be a problem using a 12volt coil on a 6 volt system.Do any of you electrical experts out there have any input?
Thanks
Georelle

Retiredgentleman · Posted: June 9, 2009, 12:45 pm Post subject: Re: Dual Coil for my Honda?

If you use a 12 volt coil on a 6 volt bike, you will only have half the required current flow. The spark would be very weak. Better look for a 6 volt coil.

georelle · Posted: June 9, 2009, 12:55 pm Post subject: Re: Dual Coil for my Honda?

RG Thanks for the help. Correct the primary voltage is only going to be 6 volts so the secondary would also be half. With that in mind would a lower resistance on the primary achieve the same thing? If the voltage is lower and resistance is lower the current would be higher. And if the coil primary to secondary ratio is higher, like on a high output coil, this should produce a high enough output. Unfortunately I can't find the specs on the original coil they are not in the shop manual.
Thans

pamcopete · Posted: June 9, 2009, 1:25 pm Post subject: Re: Dual Coil for my Honda?

georelle

Well, you are sorta correct about using a 12 volt coil with a lower primary resistance that has a high output, so there would still be a usable spark.

ikesXS 17-6803 coil might fill the bill.

georelle · Posted: June 9, 2009, 1:46 pm Post subject: Re: Dual Coil for my Honda?

Pete.
I will try that one. That is also the one used on your ignition system so if it doesn't work on the Honda I will already have my coil to do the conversion on my '76 xs. I have been wanting to make the conversion any way. So I don't really have anything to lose by giving it a try.

Thanks for the help guys.

Georelle

pamcopete · Posted: June 9, 2009, 1:56 pm Post subject: Re: Dual Coil for my Honda?

georelle

Well, I actually tested that coil at 6 volts in order to determine the performance of the PAMCO with a low battery and it does produce a usable spark. Your problem will be if the bike has an electric starter, then the voltage will drop down to 4 volts, which would be iffy. Does the bike have a kick starter?

georelle · Posted: June 9, 2009, 2:03 pm Post subject: Re: Dual Coil for my Honda?

Pete
It has both kick and electric start. I would probably always use the kicker as i do on my 650. I don't know that I would trust a 6 volt battery to start it no matter what I had for a coil. And at only 180CC kicking it can't be too hard.
Thanks again for the additional help.

Georelle

Retiredgentleman · Posted: June 9, 2009, 3:31 pm Post subject: Re: Dual Coil for my Honda?

As you say Pete, that coil 17-6803 would likely work just fine. With 6 or 6.5 volts and 2.5 ohm primary would give a current of around 2.4 to 2.6 amps, which is about 1.2 to 1.3 average current in the primary.

With the Accel coil I use, I've found that I measure average current at about 1.3 amps in the primary when I used "points" or now when I use the Pamco ignition.

pamcopete · Posted: June 9, 2009, 4:16 pm Post subject: Re: Dual Coil for my Honda?

RG

Speaking of which...how is the PAMCO working for you? Did you wire it with the coil directly to the battery?

Retiredgentleman · Posted: June 9, 2009, 5:27 pm Post subject: Re: Dual Coil for my Honda?

The Pamco is working really well Pete. I just wired it as per your instructions and its running great. It would be interesting to do the direct connection from the battery (with a 10 amp fuse). I suspect I would see a slight increase in average current, since the resistance of Ignition switch and Kill switch and one less fuse would be removed.

Maybe I'll give it a try.

pamcopete · Posted: June 9, 2009, 6:31 pm Post subject: Re: Dual Coil for my Honda?

RG

Well, that's the way I wired mine to my '81/H. It serves the same purpose as a relay, only better because there is zero resistance betwen the battery and the coil, except for the fuse. You just have to remember to remove the fuse if you are working on the ignition or coil.

I still have a relay in play, however. But I use the relay to switch the regulator to the battery so that the regulator will regulate the battery voltage instead of the "brown wire" voltage. I also connected my turn signals to the same relay contacts as the regulator to eliminate that annoying headlight dimming when the signals are flashing.

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