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Thread: O-200 Ignition Issues

  1. #1

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    O-200 Ignition Issues

    I’ve been taxi testing and running my O-200 in my Exp 11 and have a problem....it starts and runs good on both mags, but when I switch to just Left, or Just Right, it runs rough and pops and backfires. Any suggestions?

  2. #2

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    What kind of mags? Check internal timing.
    DENNY

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    cubdriver2's Avatar
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    Try running it without the leads hooked up. Shut it off with mixture or fuel

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  4. #4

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    I did run it with P leads unhooked and grounded one then the other mag....runs rough. I’ll check internal timing and harness and plugs next

  5. #5
    Cub Builder's Avatar
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    Quote Originally Posted by Dan Gervae View Post
    I’ve been taxi testing and running my O-200 in my Exp 11 and have a problem....it starts and runs good on both mags, but when I switch to just Left, or Just Right, it runs rough and pops and backfires. Any suggestions?
    Check your plug gaps, especially on the lower plugs. Weak spark combined with minimal plug gaps will cause some misfiring. Your plug gaps should be .015 - .019". You can usually run the upper plugs at .015", but will want to open up the lower plugs to .019".

    -Cub Builder
    Last edited by Cub Builder; 05-02-2021 at 09:05 PM.
    Thanks Brandsman thanked for this post

  6. #6
    wireweinie's Avatar
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    What's the history of the mags? New, used, rebuilt?

    Web
    Life's tough . . . wear a cup.

  7. #7

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    Cold cylinder check on each mag. Sounds like a plug or lead bad on each mag, but on different cylinders for each mag.


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  8. #8

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    Used mags. 200 hrs, but they are old Slick 4201s. I’ll check internal timing, but I may get new anyway...I have enough wrapped up in this project...why skimp on mags.
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  9. #9

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    I also have to a C85 sitting around with a set of Bendix S4RN-21s complete with Harness that I could put on there.....Them are the good mags. I may do that tomorrow.
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  10. #10
    Hardtailjohn's Avatar
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    Dan, check the lead placement from the cap to the plug. Sounds like the leads aren't headed to the right plug. Also, did you time it with the pin in the right hole?

    John
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  11. #11

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    What is the air temp? O-200 carbs are notoriously lean at mid power settings. Try a full power runup.

  12. #12
    cubdriver2's Avatar
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    Quote Originally Posted by CaseyO View Post
    What is the air temp? O-200 carbs are notoriously lean at mid power settings. Try a full power runup.
    Never heard that before and never had a problem like that?

    Glenn
    "Optimism is going after Moby Dick in a rowboat and taking the tartar sauce with you!"

  13. #13

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    Quote Originally Posted by Hardtailjohn View Post
    Dan, check the lead placement from the cap to the plug. Sounds like the leads aren't headed to the right plug. Also, did you time it with the pin in the right hole?

    John
    Well, I feel dumb....I had top lead wire crossed on left side after I removed them the other day to re-route through my baffeling....oops....I also had a bad plug on the right side.....I replaced 4 plugs because I had 4 new plugs....Thanks for your help.

  14. #14

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    Quote Originally Posted by cubdriver2 View Post
    Never heard that before and never had a problem like that?

    Glenn
    Perhaps notoriously was too strongly worded but it has been an issue over time, most recently experienced with a Cessna 150. It just didn't like partial power (15-1900 RPM) in the winter.

  15. #15
    Hardtailjohn's Avatar
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    Quote Originally Posted by Dan Gervae View Post
    Well, I feel dumb....I had top lead wire crossed on left side after I removed them the other day to re-route through my baffeling....oops....I also had a bad plug on the right side.....I replaced 4 plugs because I had 4 new plugs....Thanks for your help.
    Well....guess how I knew to suggest that? It happens!!
    John
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