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boyer microdigital behavior

Discussion in 'Norton Commando Motorcycles (Classic)' started by o0norton0o, Aug 19, 2018.

  1. o0norton0o

    o0norton0o

    Joined:
    Apr 27, 2015
    I have a red box boyer. As I recall it's a microdigital from the 1990's era. I also have an ammeter on my bike. I'm getting an intermittent issue where the bike doesn't start. The ammeter shows a drain on the meter just as I kick the engine over.

    If I turn the key on, the ammeter shows no drain with the lights off. The minute I roll the engine over with the kickstarter, the meter goes to the negative, showing a drain and the bike doesn't start. After a few seconds of the ammeter needle pointing into the negative, it pops back to reading Zero again...

    My thought is that the boyer is "asleep", even with the key on, but when the engine rotates, the pick up causes pulses that "Wakes up" the boyer and thats when the ammeter jumps to the negative. After a few seconds of no engine rotation (when the bike doesn't start) the boyer shuts off because there's no rotation, so no trigger signal is being sent to the boyer. Does this sound like a fair discription of how the boyer works?

    This negative ammeter behavior hasn't been the norm in the past. I wonder if I have a shakey connection on the boyer circuit or if the boyer's circuitry is dieing a slow death.

    Other thoughts are a bad cell in the battery causing some issues. I balked at buying a new battery the other day, even though one cell was low on water and the battery is pretty old. The ammeter definately indicates it's charging more strongly than usual and I keep the bike on a battery tender when it's parked... I guess I'll break down and buy a new battery and see if that helps.

    Ideas? comments?
     
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  2. tomspro

    tomspro VIP MEMBER

    Joined:
    Jan 25, 2014
    I could spend time trying to keep a Windows 98 pc running by doing core memory dumps and puzzling over .ini files. I actually did that for a living in the 90s. But I run Win 10 or Android now.
    AGM battery and modern EI will allow you to enjoy your Norton.
    We are not talking about a lot of time or money to get there.
     
  3. Mr. Rick

    Mr. Rick VIP MEMBER

    Joined:
    Feb 6, 2009
    My (non-digital) Boyer worked for many years, but then the bike started kicking back and getting very hard to start. No broken wires or obvious damage.
    Turned out the timing was far too advanced, but even adjusted back, it was still a bear to start. Why it worked well for so long with that timing is a mystery, unless I consider the possibility that it was very gradually getting more advanced as it got older. Not very likely, I know.
    In the course of looking at replacements, the Boyer MkIV digital was a contender until after review of hundreds of posts, when the impression (and no more than an "informed" impression) finally settled in that the Boyer products seem highly variable for performance, and could have been made better with better components and more QC.

    Today after no activity for a couple of weeks, the new Pazon (Altair) fired on the first kick, settled into a steady idle immediately (for the first time) and I found a bonus: previously, when restrained to low or medium RPM levels by speed limit or traffic, the bike wd "hunt" for a happy spot, wd often spit and cough if not on the throttle or slowing down. I had always put this down to poor fueling adjustment. But now she settles in to anything I want without protest. It's like a different bike, so much smoother. I hesitate to ascribe these improvements to just the Pazon, but there it is.

    You might wanna send a PM to DynoDave to learn more about your system. He prob can tell you if your idea is correct. He doesn't like to type that much; see if he will let you call him on the phone.
     
  4. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    http://www.boyerbransden.com/faultfinding.html

    "The Micro-MKIII, Micro-Digital and Micro-Power units all turn off when not being triggered,..."
     
  5. o0norton0o

    o0norton0o

    Joined:
    Apr 27, 2015
    thank you all for your comments!

    First, I'm going to replace the battery which is pretty old and see if that is the cause. It's interesting to me that when the unit is triggered the ammeter shows a surge to the negative current flow (similar to what it does intermittently when the blinker flashes) If the change of battery doesn't cure that, then I'll have to remove the fuel tank and trace the ignition wiring. Luckily, I still have my original black box boyer which still works so I can test my boyer by substitution.

    I'll report back on the results for future topic searches..
     
  6. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011
    Um, sounds like the ammeter is functioning exactly as designed.
     
    Last edited: Aug 21, 2018
  7. maylar

    maylar

    Joined:
    May 13, 2007
    I did some testing a while ago on a couple Boyer analog boxes (black) and found that after the first trigger pulse the unit would draw full coil current (about 3 amps) for about a second, then turn off. I think it's supposed to give you the strongest possible spark for starting. With the engine running it was normal current draw for the RPM and dwell time. So, if that same behavior is designed into the digital, I'd say your ammeter indication is normal.
     
  8. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    Does it spark?
     
  9. o0norton0o

    o0norton0o

    Joined:
    Apr 27, 2015
    Yeah, I think that too... and the reason the ammeter is showing greater negative deflection than normal when the boyer awakes, and shows greater positive deflection in charge mode when I'm riding is because the battery is on it's last legs. That would account for both unusual ammeter readings and also the occasional harder to start situation...

    So I'm going for the new battery solution. A Sealed AGM style. I'm pretty sure that will solve the problem. It was interesting to me that the ammeter was showing the Boyer coming on and shutting off so dramatically. It's never displayed such a noticable move of the needle when the boyer wakes and sleeps, but I supose that scenario would be the case with a weak battery. Since I keep the bike on a battery tender, it always shows good voltage, so voltage is always going to look reasonable.

    I'll report the results once I get the new battery on board...

    (and yes it sparks, it actually runs too, but you know the drill. Idling at an intersection with your headlight on make it run inconsistantly. Once I am hauing ass it runs fine and the ammeter is showing charging more than it usually does... so battery is my guess)

    Thanks again for the comments
     
  10. Triton Thrasher

    Triton Thrasher

    Joined:
    Feb 10, 2009
    Yes, could easily be that your battery lacks capacity.

    How long will your fully charged battery power the headlight with engine off, before voltage drops below 12 V?
     
  11. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011
  12. concours

    concours VIP MEMBER

    Joined:
    Dec 29, 2011
    Did you turn the headlamp off at idle to test the theory?

    Connect a set of jumper cables/battery charger while attempting to start to prove/disprove the theory.
     
    Last edited: Aug 21, 2018
  13. KiwiNeill

    KiwiNeill

    Joined:
    Jul 25, 2011
    o0norton0o
    I also have an early red box Boyer Micro Digital which works perfectly but the battery and wiring must be in top condition, which is where your problem may lie.
    I reinstated it prior to the Austria rally when my Trispark had a problem. Stuck it to the lefthand side of the Shorai battery with velcro where it still resides.
    Fitted new thinwall wires of the correct color to ignition switch, earth and stator, no killswitch. This is the start of a complete rewire.
    I use a voltmeter rather than ammeter, but with none of the effects you mention and run with the H4 headlight on all the time without idling problems.

    Set as per instructions to Mk 3 28 degrees but didn,t do the 5000rpm strobe check.
    Fired up first time and did the 2900 mile round trip to Austria and beyond with no problems, important with my electric start only setup.
    The Trispark has been replaced under warranty and will be refitted as I like the easy, accurate setup and the advance curve makes the engine seem peppier.
    However, there is alot to be said for the Boyer as it has done more trouble free miles than a Paxon Smartfire and the Trispark, so it will stay on the bike together with it,s special twin plug PVR coil as a dependable back up.
     
    Last edited: Aug 24, 2018
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