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Boyer Mark III vs Mark IV

Discussion in 'Norton Commando Motorcycles (Classic)' started by Mr. Rick, Jul 5, 2018.

  1. dynodave

    dynodave

    Joined:
    May 28, 2003
    I'd suggest to not be to reliant on a single spot sample. The accuracy of measurements on a single sample is not very convincing except for that exact device.
    In my article I show 4 samples of norton boyers to demonstrate the typical RANGE rather than a fictitious standard...
    Setting a bike up based on the "standard" is not helpful. Each mediocre device must unfortunately be set up based upon it's own sloppy tolerances.
    It is entirely possible that MR kick back device is closer to my orange line rather than the blue curve being closer to the NSW device.
    [​IMG]
    Lack of production constancy is the main contributor to a lot of the application confusion for the less technically educated. (does not mean stupid)
     
    Last edited: Jul 7, 2018
  2. dynodave

    dynodave

    Joined:
    May 28, 2003
    I don't think you need to be a rocket scientist to see how adjusting the timing for :
    A: initial timing /ease of starting
    adversely affects high RPM running OR:
    B: setting High RPM total advance for 31deg will (possibly) adversly affect starting.

    (lack of) Production consistancy is the ultimate variable that creates the situation that may result in the problems which we are now investigating again, and I had pretty much concluded and published around 2000.
     
    Last edited: Jul 7, 2018
  3. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    I agree, although I seem to remember John Healy (Coventry Spares and official US Boyer distributor for those that don't know) once saying the advance curves on the graph were 'extreme' examples. According to him the boxes don't generally vary by more than a degree or so.


    The explanation given by John Healy on the BritBike forum perhaps goes someway to answering Mr. Rick's question regarding the reasoning behind the 'slow' advance;
    http://www.britbike.com/forums/ubbt...621/re-boyer-microdigital-ignition#Post107621
    __________________________
    "The Boyer MKIII has approx. 12 degrees camshaft advance. That is 24 degrees crankshaft similar to the stock Lucas mechanical advance.

    Yes, the Lucas has more aggressive advance at low rpm and reaches full advance before the Boyer. The Boyer's "lazy" advance curve, as related to the stock Lucas mechanical, can be look upon as a benefit. With the lack of ignition and carburetion management systems and the use of modern gasoline this approach makes sense. It is one, in many steps; you should be looking at to "toughen" your motor to the ravages of detonation.

    Now, those of us old enough to have put any of T120RT or Sonny Routt's big bore kits into service is the installation of heavier auto advance springs in the auto advance assembly. Many customers are unaware that many dealer routinely installed these springs when they did a stock engine rebuild or annual tune-up. This, in the days when we still could get decent gasoline... The days of "real" gasoline are far behind us and the Boyer's use of a much slower advance curve has a lot of experience behind it.

    If you want a more aggressive advance curve, or any curve you can think of, the unit using a micro-chip (Pazon or Boyer) can be programmed by the maker to suit your requirements. Mind you should consider that you might require gasoline with an octane rating not available in [y]our area."

    ___________________________
     
    Last edited: Jul 7, 2018
  4. kommando

    kommando

    Joined:
    May 7, 2005
    My experience is at least on the digital red box there is significant difference between the boxes when keeping the stator/rotor in place unchanged and just changing boxes, the timing changes and has to be reset.
     
  5. MexicoMike

    MexicoMike

    Joined:
    Jan 31, 2010
    By doing the old school adjustment with an OEM system - advance to ping; back off two degrees, you will get the best performance you can get on whatever gas you put in. In a practical situation, the OEM curve as opposed to a Boyer (for example) curve will get the bike accelerating quicker. IOW, rolling on the throttle from a stoplight, the OEM curve would put the bike out in front and it would stay there. OTOH, if you started both machines at 5kRPM off the line, there would be no difference in acceleration though MAYBE, if the boyer continues to advance, it might get an edge there though you don't much RPM left after that. But giving up low/midrange is never a good thing. And in this case, not only are you giving up some low/mid performance, there is no practical improvement in the top end to compensate.

    OTOH, IF you are modifying an engine so as to spin a good bit more RPM than stock, there might be an advantage to increasing the advance further...or maybe not. We found that some engines turning in the 8's and above actually benefitted - depending on combustion chamber and camshaft design - on some retard at the upper end of the rev range. The problem is that a purely mechanical system cannot really do that whereas a programmed electronic can.

    We saw engines where 34 degrees of advance at 3K RPM showed the most power up to around 7500-8000 RPM but the engines liked a few degrees less beyond that RPM. Obviously, with a completely mechanical system that's almost impossible to provide. But it's no problem at all with a computer-controlled ignition.

    But even if an electronic system is totally adjustable throughout the curve, only a dyno (a real dyno, not an inertial dyno) can provide the power readings necessary to program the system for optimum performance throughout the rev range.
     
  6. dynodave

    dynodave

    Joined:
    May 28, 2003
    JH ????????????
    "The Boyer's "lazy" advance curve, as related to the stock Lucas mechanical, can be look upon as a benefit."

    spoken like a true sales man-to me quite unconvincing

    Benefit ? Mr Rick how's your ankle reacting to the "lazy advance curve".
    Isn't that entirely what we're taking about. The problem caused by a lazy advance curve?
    in addition to production variations that both exaggerate or minimize a tendency to kick back.

    MM
    "But even if an electronic system is totally adjustable throughout the curve, only a dyno (a real dyno, not an inertial dyno) can provide the power readings necessary to program the system for optimum performance throughout the rev range."

    Exactly why I got (and still have) this in 1992- 100HP brake dyno
    [​IMG]
    One of my desired next projects is to try out a programmable trispark especially for the Drouin supercharger.
    Pinging not allowed.....
     
    Kvinnhering likes this.
  7. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004

    Perhaps when Mr. Rick has set his ignition to 31 degrees (from the apparent 36 degrees full advance and 3-5 degrees advanced at lower RPMs, and ensured the Boyer is getting the required minimum voltage he will let us know? :)













     
    Last edited: Jul 8, 2018
  8. MexicoMike

    MexicoMike

    Joined:
    Jan 31, 2010
    Exactly why I got (and still have) this in 1992- 100HP brake dyno"

    COOL!! I've used a LOT of Dynos - mostly the various Mustang models - but I've never actually owned a dyno! :)
     
  9. Mr. Rick

    Mr. Rick VIP MEMBER

    Joined:
    Feb 6, 2009
    I was always getting good voltage (>13) at the battery, but have not yet tested to see if all that current is making it's way through to the Boyer.
    Somewhere out there on the Britbike Triumph forum is a routine (from John Healy!) to put a load on the circuit, so I can see what, if any, drop can be measured through the fuse holder, switch, kill-switch, connectors, etc.
    Found it: http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=670386
    Even then, I can't take the strobe readings by myself, have to wait for a buddy to work the throttle and record numbers while I peer in the hole.

    Dave C. graciously offered his number and we chatted this AM, my concerns about the "idle stabilisation feature" possibly interfering with carb tuning are allayed, and soon my money will be headed to New Zealand for the Altair unit, about US$200 . Despite the title of that thread...

    If she kicks me again during my next strobe test (or before), I'll post up some revised numbers as soon as practical.

    Thanks again, y'all, and keep yr eyes peeled for a Boyer MK IV advance curve, which I never did find...
     
  10. Kvinnhering

    Kvinnhering VIP MEMBER

    Joined:
    Feb 16, 2011
    One question. Uses Mk III and Mk IV the same stator and magnet rotor? In other words, can I only replace the black box to Mk IV and use existing stator and rotor.
     
  11. L.A.B.

    L.A.B. Moderator VIP MEMBER

    Joined:
    Nov 20, 2004
    There's only one rotor and one stator for British twins/singles.

    http://www.boyerbransden.com/products.html
    STA00152 NT1a TRI/BSA/NORTON/ENF./SING./TWIN (69mm, 2.8" Approx diameter)

    ROT00118 TRI/BSA/NORTON/SINGLE/TWIN (40mm, 1.6" Approx diameter)
     
  12. Kvinnhering

    Kvinnhering VIP MEMBER

    Joined:
    Feb 16, 2011
    Thank you L.A.B.:):)
     
  13. Mr. Rick

    Mr. Rick VIP MEMBER

    Joined:
    Feb 6, 2009
    Just an interim update, loading the system per John Healy's advice, with a jumper wire:
    There was indeed a voltage drop, from 13.02 at the battery, to 12.55 at the Boyer with it's load. Still, I don't think low voltage was contributing to the problem of kickback, and as soon as the tank is back on, I'll give it a try and hope for the best.
    I realized after pulling the rotor back by 3 degrees, that this means 6 at the crank, so may well have moved it too far, but until I can strobe it again, I won't know how much.

    MexicoMike: I read your posts, and appreciate yr comments. Sacramento is a very flat place; I've never noticed any pinging.

    I'll have the Pazon Altair ordered soon, regardless of how the Boyer ends up working. If the Altair kicks me back, I promise to report that, too.
     

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