Author Topic: Replacement ignition coil (Read 2233 times)

ukzknos · « **on:** February 17, 2010, 04:55:10 PM »

I recall once reading, but can't now find the thread, about replacement coils for the Bosch 6V 1.2 Ohm.
Can someone tell me what they are?

Thanks
Steve

Barry · « **Reply #1 on:** February 18, 2010, 07:15:17 AM »

Early aircooled Volkswagens used 6V coils. Not sure if they are 1.2 Ohms though. Eurocarparts or GSF should stock them in the UK.

Heres another source. Again the primary impeadance is not specified.
http://www.autoelectricsupplies.co.uk/product/749

steve hawkins · « **Reply #2 on:** February 18, 2010, 07:30:53 AM »

I am using a dual output second hand BMW K100 coil on my 1979 R65 - it runs with a points ignition. This was supplied and suggested by Motorworks - BMW parts suppliers. Works a treat.

This was after the 'bosch blues' kept breaking the frame mounts. They are too heavy really.

Steve Hawkins

nhmaf · « **Reply #3 on:** February 18, 2010, 10:25:51 AM »

Do you want to keep with (2) 6V coils in series, or are you interested in going to (smaller) dual output coil? I believe that VW 6V coils could work as direct replacement. If you want to go to a smaller, more compact design with dual output, in the USofA, the Dyna "Green" coil is the one you'd get for running with points and the Dyna "Brown" (Really it is orange) is the one you'd get for running with hall effect/electronic ICU.
The Dyna coils have a good track record for reliability and many of us in the states get them from Rick at Motorrad-elektrik:
http://www.motoelekt.com/ignition.htm
He also sells Bosch coils too at the link above.
There are probably sources for these items closer to you if you prefer not to have them shipped from US.

ukzknos · « **Reply #4 on:** February 18, 2010, 02:20:18 PM »

Barry

Quote

http://www.autoelectricsupplies.co.uk/product/749

These are a good price. Do you think they are a 'drop in' replacement or do I need to ensure that the resistance is the same as the standard R65 coils?

Thanks
Steve

nhmaf · « **Reply #5 on:** February 18, 2010, 02:36:43 PM »

I'm not sure if they are the same or not - I did a quick google search and found this cross reference info based on the coil number I could see on that image:
http://www.currentcare.co.uk/index.php?showprod=7320715
Check the Bosch numbers from your coil(s) against this cross list..

You would need to have a pretty good ohm meter to accurately measure the primary resistance to be 100% sure without any published info on that coil, but the odds are it would probably work with the usual 6V series wiring application.

ukzknos · « **Reply #6 on:** February 18, 2010, 02:50:41 PM »

Interesting, and even more so the place you found 'current care' is only 3 mile from my home!

JDS · « **Reply #7 on:** February 18, 2010, 03:14:14 PM »

I just took a spin around the block. It killed as I pulled into the driveway. took my helmet off and a sizzle and a puff of smoke came from under the tank, still had the key on. so I turned it off and the smoke quit. took off the tank and the coil seems to be the only thing it could have been. definitely no spark now. I was looking forward for this little break after doing taxes all morning.

Barry · « **Reply #8 on:** February 18, 2010, 03:26:12 PM »

Quote

Do you think they are a 'drop in' replacement or do I need to ensure that the resistance is the same as the standard R65 coils?

The general rule for points ignitions is that any coil with similar or higher resistance than the standard is ok. Standard coils are 1.2 to 1.5 ohms depending who you believe. Lower than standard resistance will work but the higher current will burn the points quicker and may overheat if you leave the ignition switched on without starting the bike. Electronic ignitions are able to switch higher currents and guard against overheating by turning off the coil after 5 secs if the engine isn't running.

From what I can tell one of the Bosch numbers is the standard black coil and the other is the more powerful blue coil so you should be ok. The only other issue is will the diameter fit your mounting brackets.

drewboid · « **Reply #9 on:** February 21, 2010, 12:39:33 PM »

Check out http://www.omegaignitions.com/faq.html for compatable coils. Basically if you have the ignition module (newer - electronic ignition) you can run coils with a lower primary resistance ~ 1.2 ohms total. With the older points only ignition you need the higher ohm coils ~ 2.4 ohms (or two 6v 1.2 ohm coils in series)

ukzknos · « **Reply #10 on:** February 21, 2010, 03:15:31 PM »

Quote

If you want to go to a smaller, more compact design with dual output, in the USofA, the Dyna "Green" coil is the one you'd get for running with points

Does anyone have a wiring diagram for upgrading to the Dyna coil?

nhmaf · « **Reply #11 on:** February 21, 2010, 09:36:00 PM »

I don't, but it should be fairly simple - just a (2) wires to connect the primary side and (2) connections for the spark plug leads. If you email or call Rick @ Motorrad elektric website link I provided he can give you any help/info you need on how to connect it to your points wires and suggestion on how to mount it.

Barry · « **Reply #12 on:** February 22, 2010, 06:51:29 AM »

To fit a dual output coil just connect the green/blue wire to one terminal and the two blacks to the other. The black/yellow link wire can be discarded. If your new coil has any +ve and -ve polarity markings the green/blue wire should go to +ve terminal.

steve hawkins · « **Reply #13 on:** February 22, 2010, 06:57:24 AM »

Thats what I did with my cheap K100 dual output coil.

Nobody, it seems, is as cheap as I am!

Steve H

Barry · « **Reply #14 on:** February 22, 2010, 07:04:31 AM »

Steve

How much lighter was the dual output coil compared to the heavy originals ?

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