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Crankshaft mounted ignition trigger

Discussion in 'Norton Commando Motorcycles (Classic)' started by dobba99, Sep 12, 2018.

  1. dobba99


    Jan 25, 2014
    Working through some of the problems and looking to improve the control of the ignition in the Merlin DOHC 8V
    I'm looking at the feasibility of a flywheel triggered ignition sensor mounted somewhere in the crankcase.
    This was prompted by Steve Maney quoting that having the ignition trigger on the crankshaft gave a couple of horsepower improvement over the normal cam mounted trigger.
    Easy to do if your using a belt drive without the primary drive case ( i-e racing etc) indeed Steve supplied components to do just that, mounting the trigger unit behind the engine pulley. Steve's crankcases have the timing marks already engraved on the crankcase as well.
    I'm planning for an electric start and enclosed primary drive so don't have the space between engine sprocket and crankcase/primary case.
    Any ideas anyone?
  2. kommando


    May 7, 2005
    A sensor screwed into crankcase looking at the flywheel with a toothed plate added. Alternatively a sensor looking at the teeth on the primary sprocket. Both could be handled by Secu3 https://secu-3.org/?lang=en
  3. madass140

    madass140 VIP MEMBER

    Nov 6, 2011
    I think you are on the right track. This is what i did , not suggesting. I bought Maneys ignition mainly for the Boyer box. I mounted
    the modified Boyer pickup plate on my own 3 hole alt stud mounts with standard Lucas alt in front of cNw elec start pulley. As you can see I extended the cover outwards a bit. works for me crank ign 001.JPG
    mdt-son likes this.
  4. acotrel


    Jun 30, 2012
    A friend of mine has fitted an ignition system from a VT750 Honda to his 750ss Ducati. He had trouble getting the trigger to work properly, but the bike is much better with that system. They are very cheap, but my bike has a chain primary drive with a floating sprocket.
  5. SteveA


    Dec 20, 2011
    Nitpicky, but you have posted some misinformation here. I mounted a Maney ignition on Maney cases at my first build point. The ignition trigger didn't last long, I used it in testing but not in races!

    First, the Maney trigger unit is outboard of the pulley! I would like to mount an inboard trigger, but this requires a special pulley and some form of adjustable mount for the trigger, and possible machining of the cases.

    Second, when I bought my cases Steve knew the ignition I was going to use and he provided mounting holes. There were no engraved timing marks on the cases! Unfortunately the holes were actually in the wrong place because my frame is a Rickman which mounts the motor like an Atlas. Something I told Steve, but neither he nor I realised that could be a problem.

    If you have seen an installation like this I would like to see pictures and know where off the shelf components can be bought because I don't have the skills or equipment to make my own.
    Last edited: Sep 14, 2018
  6. dobba99


    Jan 25, 2014
    I stand corrected. I didnt realise the Maney trigger was mounted outboard of the pulley, I assumed it was mounted against the crankcase as that is where the timing marks are. I didn't see them for a number of weeks after buying the cases, they are very lightly engraved, possibly only a couple of thou deep.
    Thanks to all who have replied.
  7. Chris

    Chris VIP MEMBER

    Jan 21, 2008
    Hi Dobba

    I will post a photo of a system I purchased recently.

    Kvinnhering and SteveA like this.
  8. SteveA


    Dec 20, 2011
    BTW.....Maney's Boyer box does have a different advance curve to cope with the pick up running at engine speed, not half engine speed.

    I have run that box with a camshaft pick up quite successfully, you just get half the advance range, so if you set to fully advance it is OK, but of course I use roller starters, I would not want to do that with a kick start. But clearly you cannot use a standard box with a crank pick up. Which is why Madass bought the Maney system as he mentions.
  9. Chris

    Chris VIP MEMBER

    Jan 21, 2008

    Basically a neat reversal of Steve Maneys system. I never used Steve's system as I don't run a fairing & never liked the idea of dropping the bike & destroying the mounting plate held by 3 long studs in the crankcase. The pulley has a steel piece mounted in the back of the alloy pulley. Adjustable slots in the mounting plate for the pick up. Single cylinder Boyer pick up.

    Chris IMG_20180916_150402.jpg IMG_20180916_150158.jpg
  10. mdt-son


    Jan 19, 2012
    I have played with the idea of a magneto-inductive sensor fitted to the exterior of the crankcase and picking up signals from earth magnets built into the flywheel. According to this article, measurement through non-ferromagnetic material is possble at a distance of up to 55 mm (probably much less if trough aluminium). However, the flywheel is rotating at close proximity to the crankcase.
    Thus, the crankcase need not be penetrated, enabling the sensor to be fitted on a phenolic heat protection layer and bolted outside the crankcase.
    3 countersunk magnets should enable calculation of crankshaft speed and instantantaneous crankshaft angle. There would be no adjustability of the sensor and all timing would have to be calculated electronically. Your thoughts?

    Last edited: Sep 16, 2018
  11. dobba99


    Jan 25, 2014
    Interesting article, I wonder if the magnets in the flywheel would lose some of their effect being buried in a big steel lump.
    All the suggestions above have given me plenty to think about, thanks to everyone.
    I have just started to machine the raw head casting for the Merlin (Making swarf, as a friend of mine calls it!)
    Not too happy with the quality of the metal though as it looks a bit like fine swiss cheese. Will carry on even if it ends up in the scrap bin as I will start again using a big chunk of round bar. Wish i had gone that route first as it looks like it will be cheaper anyway!
  12. Triton Thrasher

    Triton Thrasher

    Feb 10, 2009
    Crank-triggered Boyer Micro Power and insulated crimps.

    You’re in for some fun.

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