Boyer Bransden Coils Seem Wrong. Correct kit ordered.
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  1. #1
    Junior Member Fodzilla-UK's Avatar
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    Boyer Bransden Coils Seem Wrong. Correct kit ordered.

    Hi Guys

    I’ve had my Boyer Bransden kit arrive today and attempted to fit. It say us coil 0008 but came with 2 0007 coils which are reference in the instructions for Brit Bikes. Anyone else had this or should I be using them.

    Tank doesnt fit with them on so making me think the wrong ones are in the box. KIT 000293

    https://www.britishbikebits.com/boye...-cl-cb-250-350

    Instructions below.

    https://burtonbikebits.net/bbb/wp-co...9/KIT00293.pdf

    Any advice appreciated. So close to getting this thing finished.
    ‘73 CB500four - MOT,d last 2 years but in need to work/sale
    ‘81 GN400 Custom Street Scrambler
    Current Project: ‘71 CL350 Frame/ ‘75 CB350 Engine - Current Status: Turns over a couple of times on easy start

  2. #2
    Member jjdugen's Avatar
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    Hi.
    Just fitted my Boyer kit. It came with two seperate coils, can't reference the type as are fitted but if needs be can take the tank off and check.
    I fitted my pair of coils using the front mounting bolt and stand off spacers rather than the old coil bracket. All fits easily with plenty of room. BTW, I put the Micro box into the open top of the frame spine, suitably protected with a foam packing. Keeps the igniter box away from coils induced interference but does require some cable lengthening.
    I'll get some pics up in an hour or so.

  3. #3
    Member jjdugen's Avatar
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    Coil 0007 is correct. Pic of my kit.
    Attached Thumbnails Attached Thumbnails Boyer Bransden Coils Seem Wrong. Correct kit ordered.-img_20190807_132105.jpg   Boyer Bransden Coils Seem Wrong. Correct kit ordered.-img_20190807_131331.jpg  

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  5. #4
    Senior Member Sonreir's Avatar
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    Did that kit work? The offset on the pickups seems wrong for a 180° crank.

  6. #5
    Member jjdugen's Avatar
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    Works fine, just done a 100 mile run, in some pretty inclement weather too.
    Must admit, I had to do some thinking about the pick up coils but, as Bransden quote, it sparks every TDC, one of which is the exhaust stroke so is 'wasted'. I presume its to balance the rotor mass. Pity, as it will put an extra drain on the electrical supply. The difference in spark intensity is very obvious, a bright blue crack even when hand cranking the motor round.

  7. #6
    Senior Member ancientdad's Avatar
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    Quote Originally Posted by jjdugen View Post
    Works fine, just done a 100 mile run, in some pretty inclement weather too.
    Must admit, I had to do some thinking about the pick up coils but, as Bransden quote, it sparks every TDC, one of which is the exhaust stroke so is 'wasted'. I presume its to balance the rotor mass. Pity, as it will put an extra drain on the electrical supply. The difference in spark intensity is very obvious, a bright blue crack even when hand cranking the motor round.
    So your bike is a 175? (you didn't say and it isn't in your signature) The OP was talking about a CL350, which is a 180° crankshaft, and probably why Sonreir commented about the pickup positioning
    Tom

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  8. #7
    Member jjdugen's Avatar
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    CB350K2. It certainly works so the pickups must be arranged correctly. I think they operate consectively rather than as opposites. I did note that the coils are wired with a positive connection from the control module to one coil and the other input to the negative of the opposite cylinder coil. Why I am not to sure about, but I will investigate next time the tank is off and take some photos. If I can squeeze the time tomorrow I'll do that.

  9. #8
    Supporting Member fxray's Avatar
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    We talked about wasted spark on the 180° / 540° engines a couple years ago. The wasted spark, I believe, fires into the intake stroke, not the exhaust stroke on the off-cylinder. There are a couple of threads, but I think THIS ONE references the other one as well.
    It's hard to have too many motorcycles, but easy to have too many batteries and tires.

    1971 CL350K3
    1970 CB450K3
    Plus a few non-Hondas

  10. #9
    Sensei 66Sprint's Avatar
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    I'm unsure if this method was used, but there are ways that pick-up positioning could work in a 180 engine.......
    Think poles of the magnets, and/or diodes to control which way the pulse CAN go so it triggers the appropriate coil.......
    Essentially, there is only one pickup as they are wired in series......When two magnets "wipe" past the pickup coil they generate one direction of current flow which is ONLY allowed to proceed to the correct ignition coil trigger by the diodes....When the pickup is affected/influenced by the opposite magnetic polarity, the current is generated in the reverse directionality and likewise sent on appropriately by the other directionality diode to trigger the second ignition coil.....
    We use this same/similar diode set-up to separate the "sides" when using a common indicator with LED turn-signals........

    Since there are four magnets set at 90 degrees apart (like the stock points are), the pulses occur every 90 CAM degrees, but each ignition coil is only affected by/triggered during every other pulse, (so 180 cam degrees or 360 crank degrees, hence firing on both compression and exhaust)... The other ignition coil is staggered 180 crank degrees apart by the 90 CAM degree spacing.....
    Last edited by 66Sprint; 08-21-2019 at 10:21 AM.
    "I have a mind like a steel trap.....Old and rusty, of antiquated design, and hard to get stuff back out of...."
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  11. #10
    Member jjdugen's Avatar
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    66Sprint, I think you have nailed it. I had thought that the rotor magnets might be polarised N/S S/N to give much the same effect. However the pickups are phased, it all works perfectly, very pleased with mine.

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