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General Category => General Discussion => Topic started by: lucian on July 22, 2018, 05:20:53 PM

Title: Coil resistance 83 lemans III
Post by: lucian on July 22, 2018, 05:20:53 PM
I  have 0 ohm readings on both primary and secondary sides of both coils. Surprisingly the bike runs but I suspect on weak spark as grounding a plug yields only a tiny whitish sometimes blue spark so hence the coil testing. The bike has dyna ignition and I would like to replace the coils.  Does anyone know the proper resistance coil to order?  The multi meter is working fine and is one that can be calibrated( zero,d) I get 50 ohms on left HT lead and 30 ohms on rt HT lead which I assume is about right.  One coil is an original and the other is a replacement so I have no Idea if they are even the same rating and it seems they are both toast anyway.  Why it starts and runs quite well is beyond me.  Appreciate any advise.  dave
Title: Re: Coil resistance 83 lemans III
Post by: RinkRat II on July 22, 2018, 07:44:34 PM

 Should be somewhere in these ranges............. .........

(https://thumb.ibb.co/i7Wgwy/coil_checks.jpg) (https://ibb.co/i7Wgwy)


     Paul B :boozing:
Title: Re: Coil resistance 83 lemans III
Post by: guzzisteve on July 22, 2018, 08:01:02 PM
A relevant discussion not long ago---

http://wildguzzi.com/forum/index.php?topic=95516.0
Title: Re: Coil resistance 83 lemans III
Post by: lucian on July 22, 2018, 09:14:43 PM
5 ohm it is. thank you gentlemen.  Should help save a little juice for the charging system too. My guess is that the stock 3ohm coils got too hot with the longer dwell of the dyna ignition or someone left the key on too long. :embarrassed:
Title: Re: Coil resistance 83 lemans III
Post by: wirespokes on July 22, 2018, 11:16:44 PM
With electronic ignition you should be running 5K ohm caps. The resistance is needed for the coils and electronics and to produce the best spark. I'd always thought it was only for radio interference. If you're running points 1K Ohm caps will do. Run solid core wire and NGK resistor caps. You could run resistor plugs instead, but I prefer plugs without resistors.
Title: Re: Coil resistance 83 lemans III
Post by: lucian on July 23, 2018, 05:58:40 AM
I assume I would not need resistor caps or plugs with 5 OHM coils,  no?