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Thread: Horizon Tach and Slick Mag riddle.

  1. #1

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    Horizon Tach and Slick Mag riddle.

    Brand new slick mag shows that it is working, on the horizon tachometer, but it isnít.

    P leads have been checked.

    what is going on inside the mAg that it sends a signal to the tach, but creates no spark, no impulse spark or regular spark?

  2. #2
    mike mcs repair's Avatar
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    Link to tach web page for us to look at??


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  3. #3
    mike mcs repair's Avatar
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    http://www.horizoninstruments.com ?


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  4. #4
    mike mcs repair's Avatar
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    Did they forget to put a rotor in mag?


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  5. #5
    mike mcs repair's Avatar
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    Did you leave pin in mag and break rotor?


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  6. #6

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    Well, this Will be a warranty mystery that will go unsolved. Mag is fresh out of the box, so back in the box it goes. First suspected the key switch, but nope.

    This isn’t my problem, but what bugs me about this is I have a horizon Tach too, and partly the reason for having it is to tell me when I have a mag that isn’t working, but in this case, there is no indication that it isn’t working. I never knew an issue like this could exist.

    Was curious if anyone else had seen such a thing?
    Last edited by MoJo; 05-03-2020 at 05:10 PM.

  7. #7
    mike mcs repair's Avatar
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    Bench test the mag remove plead and turn over check for spark out each lead. I suspect the rotor is missing or damaged. Did they give you one someone screwed up and returned??


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  8. #8
    mike mcs repair's Avatar
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    The tach is sensing from plead/which is the lower part of mag which is doing its job, points opening and closing.


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  9. #9
    wireweinie's Avatar
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    What Mike said. Points open and close to make a signal to the tach. It's a Slick mag. If you get past the first 150 to 200 hours it should work well.

    Are you sure the mag was installed at #1 compression stroke and not exhaust stroke?

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  10. #10

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    I was told it was timed and double checked, and no banging or popping when it ran on opposite mag.
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  11. #11
    mike mcs repair's Avatar
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    Quote Originally Posted by MoJo View Post
    I was told it was timed and double checked, and no banging or popping when it ran on opposite mag.
    Need better description


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  12. #12
    wireweinie's Avatar
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    If that mag is dead and the opposite mag is installed and working correctly, there should be no 'banging or popping'.

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  13. #13
    skywagon8a's Avatar
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    Before you send it back, put it on the work bench and spin the magnet by hand with a wire connected where the harness goes, look for a spark to jump back to the mag case. If you send it back and they find nothing wrong, you are no further along in finding your trouble.

    If it works, I too suspect that it was installed incorrectly. It's easy to do.
    N1PA

  14. #14

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    Quote Originally Posted by MoJo View Post
    Well, this Will be a warranty mystery that will go unsolved. Mag is fresh out of the box, so back in the box it goes. First suspected the key switch, but nope.

    This isnít my problem, but what bugs me about this is I have a horizon Tach too, and partly the reason for having it is to tell me when I have a mag that isnít working, but in this case, there is no indication that it isnít working. I never knew an issue like this could exist.

    Was curious if anyone else had seen such a thing?
    The p lead is connected to the primary circuit, so it will only sense the low voltage side, points, condenser, p lead, and primary side of the coil. It canít sense anything on the secondary or high voltage side of the system, so the secondary coil could be open, the rotor bad, the plugs or plug wires bad.

    In your case, most likely a bad coil, bad rotor, or assembled incorrectly.


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  15. #15

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    Quote Originally Posted by dgapilot View Post
    The p lead is connected to the primary circuit, so it will only sense the low voltage side, points, condenser, p lead, and primary side of the coil. It can’t sense anything on the secondary or high voltage side of the system, so the secondary coil could be open, the rotor bad, the plugs or plug wires bad.

    In your case, most likely a bad coil, bad rotor, or assembled incorrectly.


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    This was a great insight.

    Personally, I’ve had three sets of slicks, changed or overhauled at 500-700 hours, and all have been trouble free.

    I didn’t understand the internal workings of the mag enough to understand how the P lead could give the horizon tach proper info without sending a spark to the plugs. (Right mag ran fine left mag did nothing but send rpm to the Tach) This was an education/eye opener for me and my horizon tachometer.

  16. #16
    wireweinie's Avatar
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    You need to do the basic troubleshooting here. Mag timing box will not tell you if the mag was installed incorrectly. Was the mag pinned correctly before initial install? Was it installed on the engine with #1 cylinder on compression stroke? Scenarios like these mean that the mag will fire away as normal but the spark will occur in the wrong cylinder or at the the exhaust stroke instead of compression stroke. And the tach will indicate normal function.

    As stated above, you can set the mag on a bench and check for spark. Or just take it to a mag shop and have do a functions check. Verify this before just sending it back without knowing the root cause of the issue.

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  17. #17

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    Quote Originally Posted by wireweinie View Post
    You need to do the basic troubleshooting here. Mag timing box will not tell you if the mag was installed incorrectly. Was the mag pinned correctly before initial install? Was it installed on the engine with #1 cylinder on compression stroke? Scenarios like these mean that the mag will fire away as normal but the spark will occur in the wrong cylinder or at the the exhaust stroke instead of compression stroke. And the tach will indicate normal function.

    As stated above, you can set the mag on a bench and check for spark. Or just take it to a mag shop and have do a functions check. Verify this before just sending it back without knowing the root cause of the issue.

    Web
    This isn’t my bird to call the shots, and it is in the hands of experienced mechanics, so I would think this was done. I have seen a mag set 180 degrees, sounds like the 4th of July.

    Is it possible to time out of phase and have perfect silence on the bad mag?

  18. #18
    skywagon8a's Avatar
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    Quote Originally Posted by MoJo View Post
    This isn’t my bird to call the shots, and it is in the hands of experienced mechanics, so I would think this was done. I have seen a mag set 180 degrees, sounds like the 4th of July.

    Is it possible to time out of phase and have perfect silence on the bad mag?
    My Pmags fire at both the compression and exhaust strokes without any misfiring. No 4th of July noises.
    N1PA
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  19. #19
    mike mcs repair's Avatar
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    Horizon Tach and Slick Mag riddle.

    [

  20. #20
    CamTom12's Avatar
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    Quote Originally Posted by skywagon8a View Post
    My Pmags fire at both the compression and exhaust strokes without any misfiring. No 4th of July noises.
    True, mine do the same. But if they only fired on the exhaust stroke Iíd bet thereíd be some fireworks as the mixture ignited and traveled down the exhaust stack while still burning.
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  21. #21
    180Marty's Avatar
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    I have removed the plug from my lawn mower and pressed it against the cylinder head and pulled the rope to check for spark. Never tried a dual plug engine that you can compare sparks before.

  22. #22
    wireweinie's Avatar
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    With an impulse coupled mag, it works the same. Just don't make a mistake while holding it!

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  23. #23
    skywagon8a's Avatar
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    Quote Originally Posted by CamTom12 View Post
    True, mine do the same. But if they only fired on the exhaust stroke I’d bet there’d be some fireworks as the mixture ignited and traveled down the exhaust stack while still burning.
    Perhaps, but only if the good mag was shut off.
    N1PA
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