R50/2 ignition help needed

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

  1. Beamer Bum

    Beamer Bum Been here awhile

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    Dec 31, 2010
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    825
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    Working to support a bike addiction
    Yep, but if you leave the center conductor of the wire too long, the lowest resistance is thru the spark gap. DAMHIK
    #41
  2. danedg

    danedg Horizontally Opposed

    Joined:
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    8,032
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    Wabanaki Trail
    And furthermore!....
    If you ever get to meet Vech, more than likely he will pierce you in the eye with his gaze, and in that slow drawl, will growl at you that you need to guarantee the absolute ground between the magneto and the points carrier plate. (The brass one.)
    [​IMG]

    See the 4 big crews on the corners?
    Remove the whole assembly from the magneto and refresh all contact points. I can still hear Craig muttering about about all those NY noobs...:(:
    The points aren't providing juice, they are creating ground. They can't do that unless they have perfect ground.(zero resistance).
    And to answer your timing question... see the screw directly below the points?
    That secures the points. The screw to the right ADJUSTS your points.
    #42
  3. Monkeyboy71

    Monkeyboy71 Adventurer

    Joined:
    Mar 5, 2017
    Oddometer:
    16
    Following that round of advice I:
    • Switched the plugs from side-to-side just to rule out a bad plug. It fires fine on the opposite side. When I pulled the plug from the left side, the side that was not firing regularly and/or backfiring, that plug was pretty wet.
    • Trimmed up the copper ends to get the 11MM gap. To test the potential of an arch issue, I pulled a plug wire while it's running and it arched, but it did not arch while running so long as the wire was attached to the plug.
    • @Beamer Bum, what is the "inductive pickup?" I did shine the timing light at the advance unit at idle and saw only 1 image.
    So maybe it is the carbs. They are not "dialed in" at all. I did just watch the video on how to set the idle so we'll give that a go now. I'll start with the air-idle mixture and then set the throttle.
    #43
  4. Monkeyboy71

    Monkeyboy71 Adventurer

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    Ok, so I took the air-idle screw all the way in on both sides, back it out 2 full turns and locked it down. Fired up and idled pretty smoothly. Yanked the plugs one at a time and it idled a little rough and tried to die. So that's pretty close and much, much better.

    Now, what I did do was check the timing again. Firing from the left side, the timing is sketchy. It's almost like it's advanced; it's hitting close to the F than the S. But when testing from the right side plug, it's more consistently hitting the S mark. So that would make me question something on the timing, still.

    I think I'm going to go do some mechanical items for an hour or two and let this just sort of soak in. Put fresh eyes back on it in a bit.
    #44
  5. Beamer Bum

    Beamer Bum Been here awhile

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    The inductive pick up is the trigger for the timing light. It's the piece that clips over the spark plug wire. Some timing lights are sensitive to the orientation of the pick up. If you have an intermittent trigger of the timing light, flip the pick up over on the spark plug wire. If you have a consistent trigger, don't worry about it.

    From what you describe ( one cylinder at S mark, the other cylinder closer to the F mark), you have differential timing. The camshaft rotates at 1/2 the speed of the crankshaft, so there are two lobes on the cam to open the points. One lobe is opening before the other one. The early lobe is also opening the points more
    (greater than 16 thou.)

    There are several ways to deal with this. Since it sounds like yours isn't real bad, we can try the easiest way. The tip of the camshaft is tapered and the magneto has a corresponding cone shape which fits over the cam. You can adjust how the two fit by a small amount by tapping the cone to one side.
    Rotate the engine so the side which opens early (advanced) opens the points to maximum lift.
    [​IMG]

    Carefully remove the advance unit without rotating the engine. Take a wood dowel and a hammer and gently TAP the tip of the magneto towards the left side of the engine. You are only trying to move it by thousandths of an inch.
    [​IMG]

    Re-install the advance unit and check static timing on both cylinders. Repeat above steps until both sides are equal. This will move both cylinders timing. Th F (advanced cylinder) should move towards the S and the S (normal cylinder) should move towards the F. Then re-set the timing and you should be good to go.
    #45
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  6. Monkeyboy71

    Monkeyboy71 Adventurer

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    Oddometer:
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    Ok, we're super close. It's running pretty well and the timing is closer. The only two remaining issues are 1) need to adjust the front brake, which is easy enough and 2) the gear box is noisy. It's a fresh build and full of gear oil so it should be nice and tight. But it sounds like something is loose, as if some gears are clattering around. I'm going to dig back into that layout and make sure I didn't miss anything when putting it all back together. Actually, now that I think about it, it might just be the clutch needs adjusting. We'll start there.
    #46
  7. olefartRich

    olefartRich Senior Discount . . .

    Joined:
    Jun 12, 2015
    Oddometer:
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    Somewhere in Texas
    Many of the photos are gone today (10/13/2021) but this thread has been helpful, thanks!
    #47
    korinthias likes this.
  8. LBourque

    LBourque G/S nut

    Joined:
    Nov 2, 2010
    Oddometer:
    925
    Location:
    Northern AZ
    I couldn't agree more! I'm troubleshooting a 1965 R60/2 and this thread has been very helpful as well as Benchmark!
    #48