R50/2 ignition help needed

Discussion in 'Airheads' started by Monkeyboy71, Mar 7, 2017.

  1. Monkeyboy71

    Monkeyboy71 Adventurer

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    I am trying to get spark on my father-in-law's R50/2 engine. The internals were professionally rebuilt a few months ago, but rest of the bike is original, including the ignition. He said that the in the 90s the magneto stopped working, so he hooked up a 6v Harley coil and drove it like that for a while. I'm looking to remove that from the mix and find the actual issue and repair it so that I can get some spark. I could use some guidance on how to test this out, because I'm getting no spark with or without his coil bypass.

    After a great deal of reading and studying diagrams I have a few questions:

    1) The wire to the coil, points and condenser is a ground, right?

    2) If that's the case, where is the positive connection coming from? I do not see where it would be.

    3) How do I test the coil or condenser? Is that a continuity test resulting in a certain range?

    4) Anything else I should test before I just buy a replacement coil and condenser?

    Note: I have set the point timing, but that's the only adjustment I have made.

    Thanks in advance.
    #1
  2. Brun

    Brun Been here awhile

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    Welcome aboard, Monkeyboy71. I know very little about the /2 bikes apart from knowing that I like them a lot. Others will be along shortly but in the meantime I'll offer this: a magneto is 'self-energising'. The spark voltage is produced when the magneto rotates.

    [​IMG]

    That Brown/Black wire coming from the magnetz├╝nder is the kill wire. It is grounded when the ignition is turned off and disconnected from ground when the ignition is turned on. You can disconnect that wire to bypass the ignition switch.
    #2
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  3. tlub

    tlub Long timer Supporter

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    Except for that kill wire, nothing in here has anything to do with spark. The magneto is self energizing (or apparently not in this case). There is no positive. They run the same with and without a battery or any other source of 6V. That being said, a bad coil, like you father experienced in the past is the way these things die. Bench Mark Works, Motorad Elektrik, and others have replacements.
    There has been much written on this. Go to w6rec.com (Duane's site) for a primer. He is an expert and it has all be said. Call Vech at Bench Mark Works if you need more help. Or Rick at ME. There are others, too- those are the first two that come to mind. You absolutely should have new solid wires (NOT resistor wires) and NOT resistor plugs or caps. There is little enough voltage being generated at kicking speeds without reducing it further with resistor anything.
    Remember this is a magneto that is not like any other ignition system you may have seen, unless you work on aircraft piston engines. And then the /2 mag does not have an impulse coupler like aircraft, so it is worse. It all depends on the proper E-gap (Abriz) and good clean, conductive, properly fucntioning everything.
    But it sounds like you need a coil.
    If you are asking about how to wire the 6V coil to the battery, it is just 6V+ lead to one coil terminal, the other to points and condenser. The circuit is completed by the points completing the ground.
    #3
  4. chasbmw

    chasbmw Long timer

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    I would start off by replacing the coil and the condenser, these are the parts that often fail on a /2, the blue plastic covered coil made by Emerald Isle and sold by their stockists (Rick, Motorworks etc ) is the coil to buy, it's properly made and will really help maintain the bikes reliability, one you have done that clean the points and scheck the gap and she will probably start.

    Checking ignition timing is a PIA, mainly because there is so much mechanical slop in the system, that getting the timing nearly right seems to be a matter of luck!

    There is an ignition cut out operated by the ignition switch, that will stop the magneto sparking, but unlike a later coil ignition a magneto doesn't need power from the battery to work.
    #4
  5. Pokie

    Pokie Just plain Pokie.

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    Just for testing purposes, there is a wire that grounds the magneto (screw down fitting) on the upper left side of the magneto, (will likely be a black or black with red stripe or a brown with black stripe) just above the coil mount. If you disconnect this wire, you should have spark all the time, by-passing the ignition. When you disconnect this wire, it removes any magneto ground in the system. Why I ask to have this wire disconnected for testing is some owners fitted the bike with a hidden grounding switch to make it so the bike won't run for a would be thief.

    Make sure the flux is adjusted properly (notch on the timing plate aligning with the notch or mark on the magneto rotor). The points should have about .016" gap at it's most open point. The points should be just breaking or just opening at the "S" mark on the flywheel. Always rotate the crank in a clockwise direction, if you want to back up the crank to take a quick check, always rotate the crank way past the "S" mark, then come up to the "S" mark turning in a clockwise direction. NEVER turn the engine with the bolt on the cam, this is too stressful on the cam bolt. When you check the timing (manually with an OHM meter or light ) always disconnect the wire at the points that goes to the condenser, hook the condenser wire back up for running or spark testing.

    If after adjusting you still don't get spark or get spark only on one side or irregular spark, it's likely the coil is at fault.
    #5
  6. deafanddiabetic

    deafanddiabetic Would rather be wrenching.

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    Isn't this place great? Sometimes I just get stoked.
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  7. danedg

    danedg Horizontally Opposed

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    Replace the condenser and spark plugs first. Check continuity of the wires and caps and plugs and make sure they read zero.
    Remove the plugs and lay (ground) them on the cylinder with the caps/wires attached.
    Kick the bike over (you can do it by hand with the plugs out) and you should see a big fat blue spark on the business end of the plug.
    Report back....
    Welcome aboard!
    #7
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  8. danedg

    danedg Horizontally Opposed

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    By installing that Harley coil in the loop the old man created a Battery/Coil ignition setup.
    Meaning the ignition is fired by the battery. Worked fine as long as your battery was up to snuff.
    The bike originally used a magneto fired ignition, eliminating the need for a battery other than powering the lighting system.

    Google up "Understanding and Maintaining the /2 electrical system" by Doug Rinckes.
    Call me in the morning....
    #8
  9. tlub

    tlub Long timer Supporter

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    :lurk
    BTW E-gap= abriz= flux. We're all saying the same thing.
    #9
  10. Beamer Bum

    Beamer Bum Been here awhile

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    This is what we are talking about. With the flywheel S mark in the window align this mark on the magneto with the notch in the housing. (Yours won't be painted like mine is. Unless you want to paint it so it's easier to see :-))
    [​IMG]
    #10
  11. danedg

    danedg Horizontally Opposed

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    A picture of your bike's setup would be very helpful.
    #11
  12. danedg

    danedg Horizontally Opposed

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    I think we lost him.....
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  13. tlub

    tlub Long timer Supporter

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    I'm not sure we ever really had him. Seemed like maybe getting in too deep too fast as far as magneto university goes.
    #13
  14. Pokie

    Pokie Just plain Pokie.

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    Its often confusing for folks that don't know or understand magnetos. For some reason, they just can't imagine something producing spark without a battery. I'm sure he'll chime back in when he's ready.
    #14
  15. Monkeyboy71

    Monkeyboy71 Adventurer

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    Sorry for the slow reply; the week got away from me. I very much appreciate this information. You guys are amazing!

    You are correct, Pokie, I'm surprised the battery is not involved here. But then that does make more sense to me now and, in hindsight, seems pretty obvious given the single wire running into the magneto (that has moving metal near magnets).

    I have removed the 6v coil from the equation and wired everything according to the diagram. Here's the photos:

    The static timing mark:

    [​IMG]

    The flywheel mark, shot from off center so it looks less properly set than it is:

    [​IMG]

    And lastly the entire front set up, taken while the spark plug wires were not connected:

    [​IMG]

    I'm confident in the wiring into the magneto and and timing being set. Tested again just now, no spark.

    I did find the coil and condenser and will order them today. Not worried about 200 bucks for those parts as it sounds like if I don't need them now, I'll need them eventually.

    Thanks, fellas, for the help!

    Kyle
    #15
  16. danedg

    danedg Horizontally Opposed

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    Ummmm...
    You don't need the magneto if you're battery/wired to the coil.
    If you're gonna use the magneto the coil needs to be connected to the plugs.
    #16
  17. Monkeyboy71

    Monkeyboy71 Adventurer

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    The wires are plugged in during testing, I just had them out when I took the photos. Since I can't get any spark from battery/wire combo, I figured I might as well remove those and test the original magneto/coil combo, which also gets no spark.
    #17
  18. danedg

    danedg Horizontally Opposed

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    The generator looks lo mileage.
    How many miles showing on the clock?
    #18
  19. danedg

    danedg Horizontally Opposed

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    Kyle,
    Please read through the following link. It's not long...
    #19
  20. Monkeyboy71

    Monkeyboy71 Adventurer

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    Danedg, I appreciate the share of the PDF. That's got some great, easy-to-understand, info in there.

    The odometer reads 35,xxx. And I don't think the generator has been updated or replaced.
    #20