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Author Topic: replacement coils  (Read 4088 times)

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ZombieBike

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replacement coils
« on: April 11, 2005, 08:40:51 AM »
So now that I have that tank issue taken care of (thanks for everyones input) I have to tyurn my attention to my ignition coils. The bike I am fixing up hasn't been running in probably 15 years or so and the igntion coil wires are junk. All the ignition coils I seem to find though are high performance ones that cost a lot of $$$. Whats the cheapest route to get this thing back to life...other than buying a running bike (which I have considered)..thanks again, Kyle
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Offline Gordon

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Re: replacement coils
« Reply #1 on: April 11, 2005, 08:50:25 AM »
http://crc2onlinecatalog.com/Index_Main_Frame.htm has replacement coils for 45 bucks each if you want to go new.  And there's always ebay for used ones.  You can get a set from a newer bike that puts out a stronger spark and has replaceable wires.  The main thing you need to look for is that the mounting points are the same.  Most of the coils from any of the 80s Honda 4cyl bikes will fit the 500 -750 sohc4. 
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Ibsen

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Re: replacement coils
« Reply #2 on: April 11, 2005, 08:53:39 AM »
If the coils otherwise is ok when you measure the resistance in the primary and secondary windings, you can upgrade the wiring to the coils and get more power to them at the same time.
Take a look at this thread:

http://www.sohc4.us/forums/index.php?topic=313.0

And if the plug wires is bad but moulded into the coils, you can cut the old ones a couple of inches from the coils and splice on new wires. NGK are selling wire splicers for plug wires, or you can solder them together and use a piece of heat-shrink tube as insulation.
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gerstle

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Re: replacement coils
« Reply #3 on: April 11, 2005, 08:58:35 AM »
ZombieBike - I'm in the middle of a restoration project and was planning on upgrading my coils to those nice new accels.  If you don't have any luck and you want stock coils/wires off of a '73 750 (daily rider in january when i tore it apart) you might try emailing me in a week or two (kinda busy at the moment) and we could work something out.  gerstle@gmail.com
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ZombieBike

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Re: replacement coils
« Reply #4 on: April 11, 2005, 01:13:16 PM »
I know at one point I knew how to test coils, but perhaps someone would be willing to give me a little refresher course? I have a fluke multimeter, I think I am going to need that, right? kyle
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Ibsen

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Re: replacement coils
« Reply #5 on: April 11, 2005, 03:05:01 PM »
Yes you will need a multimeter set to ohm range. And the coils must be disconnected. And when you measure the primary winding between the + and the - lead, or connectors, you should have 3,2~4,8 ohms. Then set the meter to Kilo ohms range and measure the secondary winding  between the plug caps. The resistance should be 13~15 kilo ohms. But if you are using plug caps with 5 Kilo ohms resistors, the reading will be 23~25 Kilo ohms.
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Offline cben750f0

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Re: replacement coils
« Reply #6 on: April 11, 2005, 04:07:39 PM »
the primary ohms reading on my coils off the F1 were 5.5-5.7... and the secondary was 14kohms- 15kohms... oh and one coils showed open circuit... thats why i am usung the VFcoils...peace
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you are never to old, to act like a kid... be safe
funny thing,chasing someone down hill on a bike 30 years older than theirs..
he said \\\\\\\'it was like watching a 250kg unguided weapon getting stuck up you bum\\\\\\\ http://www.bikepics.com/members/trixtrem/

ZombieBike

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Re: replacement coils
« Reply #7 on: April 12, 2005, 09:04:35 AM »
awesome, when I get home this weekend (bike is at my parents house, I am at school) I will be testing the coils. I can't wait...this forum has been a godsend, thanks everyone! Kyle
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Offline cben750f0

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Re: replacement coils
« Reply #8 on: April 13, 2005, 06:46:10 AM »
also mate if you want a better spark, check the FAQ  ignition and coils post... it has a diagram for wireing a relay in to take power from the battery straight to the coils... heaps better spark... i have also posted some pics of the job i didhttp://www.sohc4.us/forums/index.php?topic=313.0..peace and have fun...
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you are never to old, to act like a kid... be safe
funny thing,chasing someone down hill on a bike 30 years older than theirs..
he said \\\\\\\'it was like watching a 250kg unguided weapon getting stuck up you bum\\\\\\\ http://www.bikepics.com/members/trixtrem/

ZombieBike

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Re: replacement coils
« Reply #9 on: April 14, 2005, 05:21:09 PM »
Alright, so I tested the coils...the results are in...coil 1: primary winding = 4.4 ohms secondary winding = 14.26 kilo ohms...coil 2: primary = 4.1 ohms secondary = 29 kilo ohms! Damn, so close...so I just need to replace one...well, that'll be cheaper than 2 I bet ;) Or should I replace them both anyway, can you replace just one? Thanks. Kyle
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Offline cben750f0

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Re: replacement coils
« Reply #10 on: April 14, 2005, 07:09:49 PM »
mate was that with caps on or off?... it will be different if they are on or off... peace
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you are never to old, to act like a kid... be safe
funny thing,chasing someone down hill on a bike 30 years older than theirs..
he said \\\\\\\'it was like watching a 250kg unguided weapon getting stuck up you bum\\\\\\\ http://www.bikepics.com/members/trixtrem/

ZombieBike

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Re: replacement coils
« Reply #11 on: April 15, 2005, 08:03:58 AM »
caps on or off?
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