Author Topic: What is this bit linked to the Coils  (Read 732 times)

Offline Eldrick

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What is this bit linked to the Coils
« on: March 20, 2023, 05:31:35 PM »
What is this bit  linked to the Coils?

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It was zip-tied under the fuel tank, at the rear, under the rubber cusion and the wires go to each coil.
Is it a genuine part and should it be under the tank? It works, as in the bike starts but as I am re-wiring it with a new loom I want to know what it is and where it should live.
Thanks.
1975 Honda CB400f - Red

Offline Multiman

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Re: What is this bit linked to the Coils
« Reply #1 on: March 20, 2023, 05:42:05 PM »
Could it be a junction box?
Does it open?

I've just rewired my 400/4 and the loom to coils connection is under the tank, but just sleeved bullets so I assume this is a mod you have.

Here's an image of mine.
Ignore the fact that the coils are the wrong way round.
Ignore the fact that both coils have a yellow and black instead of one having a yellow and black and the other a blue and black (after market coils, the starboard coil is the one that should have a blue wire and is for pots 1&4)
Ignore the fact that it has no carbs on it, (this could be a clue to to the poor running)


« Last Edit: March 20, 2023, 05:52:30 PM by Multiman »

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: What is this bit linked to the Coils
« Reply #2 on: March 20, 2023, 05:45:04 PM »
Whatever it is its not standard.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
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Offline K2-K6

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Re: What is this bit linked to the Coils
« Reply #3 on: March 20, 2023, 05:49:00 PM »
From the colours of wire and number of them, plus linked to coils, suggests it's electronic switching of coils, possibly.

Does the wire route go to just the coils ? Or points ? Is it interlinked with those ?

More pictures of it to see detail. 

Offline Eldrick

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Re: What is this bit linked to the Coils
« Reply #4 on: March 20, 2023, 05:58:22 PM »
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This is how it links to my coils,  there  is also one other wire, a ground, that connatcs to the frame under the seat.
The box does not open, it is a sealed unit.
It does not itself connect directly to the points.
« Last Edit: March 20, 2023, 06:00:38 PM by Eldrick »
1975 Honda CB400f - Red

Offline Johnwebley

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Re: What is this bit linked to the Coils
« Reply #5 on: March 20, 2023, 06:00:07 PM »
It looks like an early Boyer ignition  box

Check under the points cover

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Offline K2-K6

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Re: What is this bit linked to the Coils
« Reply #6 on: March 20, 2023, 06:02:34 PM »
John beat me to it  ;D look under the points cover to see what's there.

Another picture  :)

Offline Eldrick

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Re: What is this bit linked to the Coils
« Reply #7 on: March 20, 2023, 06:06:43 PM »
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OK, just looked there, I know nothing about that so here is a photo.

1975 Honda CB400f - Red

Offline K2-K6

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Re: What is this bit linked to the Coils
« Reply #8 on: March 20, 2023, 06:13:32 PM »
Yep, electronic ignition.

That bit provides the timing pulse as the crankshaft rotates, then the box up by the coils interpretss that signal and switches the coils on and off to make the sparks.

Offline Eldrick

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Re: What is this bit linked to the Coils
« Reply #9 on: March 20, 2023, 06:16:02 PM »
Yep, electronic ignition.

That bit provides the timing pulse as the crankshaft rotates, then the box up by the coils interpretss that signal and switches the coils on and off to make the sparks.
Is that a 'good thing'? I guess if the bike isn't broke don't fix it is my first thought, if anyone has different thoughts, let me know.

thanks.
1975 Honda CB400f - Red

Offline Johnwebley

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Re: What is this bit linked to the Coils
« Reply #10 on: March 20, 2023, 07:38:29 PM »
My personal opinion is it's great

Have it on my 500,


Search Boyer ignition

Its still being made
Instructions and wiring diagrams can be seen, and downloaded

Read,

Ask any questions,



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Offline Johnwebley

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Re: What is this bit linked to the Coils
« Reply #11 on: March 20, 2023, 08:15:02 PM »
My personal opinion is it's great

Have it on my 500,


Search Boyer ignition

Its still being made
Instructions and wiring diagrams can be seen, and downloaded

Read,

Ask any questions,



Sent from my SM-A750FN using Tapatalk


  just got on the website
http://www.boyerbransden.com/pdf/KIT00055__BOX00014_.pdf


  other info available,

  use   resister  plug caps,  NOT resister plugs

  ideally  have your ignition timing  checked  with a strobe,

 




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Offline K2-K6

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Re: What is this bit linked to the Coils
« Reply #12 on: March 20, 2023, 08:29:43 PM »
Definitely a good system.

Replaces the Honda's points/mechanical system ( good in itself) with electronic triggering and switching with effectively no wear items.

Usually very reliable too.

Offline McCabe-Thiele (Ted)

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Re: What is this bit linked to the Coils
« Reply #13 on: March 20, 2023, 10:49:43 PM »
Anyone know what the extra  current draw is to power the transistor box?
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Offline Bryanj

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Re: What is this bit linked to the Coils
« Reply #14 on: March 20, 2023, 11:04:13 PM »
The box very little but boyer tend to fire the coils together so the coil load is doubled

 

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