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  1. #1
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    lawn mower spark plug question

    My mower with a Honda engine had a failed plug and being the pack rat that I am had some old used ones from my Odyssey on my bench. The thread fits and I give it a pull and the damn thing fires up and runs better than it's ever run just in time to mow before it rains and in time for me to watch that bitch Baker Mayfield get hounded all monday night. The "new plug" has a smaller head and about 1/16" longer in the electrode part that inserts into the combustion chamber but it obviously the engine fires up and runs. As long as it operates am I risking any (further) damage ? This is a iridium plug vs. original copper OEM for the mower. There has to be quite a few former neighborhood lawn cartel guys and landscape crew vets that pushed mowers all summer baked out of their minds. Let's hear it from all the mag small engine experts.

    Looked at the specs of each plug and the reach is the same BUT the electrode of the iridium plug(new one from my car) seems slightly longer than the OEM copper.
    Last edited by fatnslow; 10-08-2019 at 11:48 AM.

  2. #2
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    Aftermarket non original spark plug could cause your mower to fail the state required annual inspection.
    Go that way really REALLY fast. If something gets in your way, TURN!

  3. #3
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    if the heat range is similar, you're good to go.

  4. #4
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    You’re gonna die.
    And I guess that I just don't know

  5. #5
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    As long as the VTEC kicks in you're fine

  6. #6
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    Quote Originally Posted by SumJongGuy View Post
    Aftermarket non original spark plug could cause your mower to fail the state required annual inspection.
    pre 76 so no emmisions AND I lived to post about it. Maybe if I use one from my mercedes it'll run like an AMG DD style .

  7. #7
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    Quote Originally Posted by fatnslow View Post
    pre 76 so no emmisions AND I lived to post about it. Maybe if I use one from my mercedes it'll run like an AMG DD style .
    Or if you live in an urban area, you can have a friend register your mower in their rural county that does not require annual emissions inspections.

  8. #8
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    If the piston in the mower hits the plug tip, you'll know pretty soon.

    IMHO for the cost of getting the correct plug, this isn't worth it.
    Quote Originally Posted by powder11 View Post
    if you have to resort to taking advice from the nitwits on this forum, then you're doomed.

  9. #9
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    Quote Originally Posted by El Chupacabra View Post
    IMHO for the cost of getting the correct plug, this isn't worth it.
    +1

    Plugs are cheap. I run a lot of saws, I wouldn't do this.
    At least not without verifying compatibility with a verified source like honda or a small engine mechanic - beyond us tgr clowns. We're dentists anyway.
    Cylinder temps, complete fuel combustion, valve performance, piston/ring health, oil consumption .. maybe some things that won't show right away but will ultimately destroy the unit.
    Improve performance other safer ways: fresh ethanol free fuel, properly tuned carb, regular maintenance etc.

    with that said, it'd be sweet if the van plugs were given the official blessing. let us know!

  10. #10
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    Quote Originally Posted by MiddleOfNight View Post
    +1

    Plugs are cheap. I run a lot of saws, I wouldn't do this.
    At least not without verifying compatibility with a verified source like honda or a small engine mechanic - beyond us tgr clowns. We're dentists anyway.
    Cylinder temps, complete fuel combustion, valve performance, piston/ring health, oil consumption .. maybe some things that won't show right away but will ultimately destroy the unit.
    Improve performance other safer ways: fresh ethanol free fuel, properly tuned carb, regular maintenance etc.

    with that said, it'd be sweet if the van plugs were given the official blessing. let us know!
    Took a look at the NGK specs and the reach for both plugs are the same and the temp is 5 vs 6 on their range, very minor temp differnce. In fact if you look at other plug manufacturer temp charts the two ranges fall within the same temp range. The only differnce is the actual electrode seems slightly longer on the iridium(van) plug. Not a price savings since the OEM copper are only a few dollars and the iridium are much more. I was just trying to confirm if the magnito was working and the old plug just didn't fire so I pulled the used one to check spark and for the hell of it checked to see if it threaded in the block. It fired up easier than I ever remember this thing running in years, even after a new correct plug installed previously. I have 5 more used iridium plugs so it might last me the life of the mower or rest of my life. Every small engine repair place acts like their service is top secret and what they do can't be replicated by ANYONE. My only concern is the piston contacting the electrode per El Chupacabra but would assume it would have made some noise when it was running. Planning on pulling and taking a look tonight at the plug.

  11. #11
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    Quote Originally Posted by Dee Hubbs View Post
    Or if you live in an urban area, you can have a friend register your mower in their rural county that does not require annual emissions inspections.
    I can always use the tags from my van since it's using the van plugs.

  12. #12
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    Wait a minute. There are emissions restrictions and inspections on a lawnmower? And people actively bring them in to get inspected? Dafuq!

  13. #13
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    Quote Originally Posted by 2FUNKY View Post
    Wait a minute. There are emissions restrictions and inspections on a lawnmower? And people actively bring them in to get inspected? Dafuq!
    Oregon is very progressive. When I rip farts I have to pay a methane emissions tax as well

  14. #14
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    Quote Originally Posted by fatnslow View Post
    Oregon is very progressive. When I rip farts I have to pay a methane emissions tax as well
    Well that stinks........

  15. #15
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    Pulled the plug and no signs of actual contact but is is pretty fowled after one mowing. Maybe try replacing with oem spec plus and fresh gas and see what happens. Don't know shit about small engines and what is normal. Never seen car plugs get this much carbon build up so quickly.

  16. #16
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    Not hot enough.

  17. #17
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    Quote Originally Posted by fatnslow View Post
    My mower with a Honda engine had a failed plug and being the pack rat that I am had some old used ones from my Odyssey on my bench. The thread fits and I give it a pull and the damn thing fires up and runs better than it's ever run just in time to mow before it rains and in time for me to watch that bitch Baker Mayfield get hounded all monday night. The "new plug" has a smaller head and about 1/16" longer in the electrode part that inserts into the combustion chamber but it obviously the engine fires up and runs. As long as it operates am I risking any (further) damage ? This is a iridium plug vs. original copper OEM for the mower. There has to be quite a few former neighborhood lawn cartel guys and landscape crew vets that pushed mowers all summer baked out of their minds. Let's hear it from all the mag small engine experts.

    Looked at the specs of each plug and the reach is the same BUT the electrode of the iridium plug(new one from my car) seems slightly longer than the OEM copper.
    Should we all pitch in a penny so you can afford a fucking spark plug?

  18. #18
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    Go that way really REALLY fast. If something gets in your way, TURN!

  19. #19
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    Quote Originally Posted by 3PinGrin View Post
    Should we all pitch in a penny so you can afford a fucking spark plug?
    No shit...! I paid $600 for my Honda and paying $5.37 for my OEM spark plug almost broke the bank... You can tell it has been a long time since we have all skied as this thread is one of the more exciting threads in a while...

    Sent from my SM-G955U using TGR Forums mobile app

  20. #20
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    Quote Originally Posted by Undertow View Post
    You can tell it has been a long time since we have all skied as this thread is one of the more exciting threads in a while...
    for sure, snowing good in Montana tonight though, it's coming....

  21. #21
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    Hmmm, thinking about adding some ghetto rocker to the cutting blade to add artisan fade to my lawn before it rains for the next 6 months.

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