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Resistor Spark Plugs?

Discussion in 'Chainsaw' started by Philbert, Jan 30, 2010.

  1. Philbert

    Philbert Chainsaw Enthusiast

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    Does it make any practical difference if I use a resistor or non-resistor plug in a chainsaw?

    If not, why do they go out of their way to specify the resistor plugs?

    Thanks.

    Philbert
     
  2. Trigger Man

    Trigger Man Addicted to ArboristSite

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    I had that same question on my mind 2 years ago, I emailed NGK and they responded to it by telling me to use the same plug that the Manufacturer used period.

    Most small engine shops that I have been to say that the resistor is for radio interference.

    I have also read that some ignitions talk back and forth to the resistor, I'm trying to find that info If I find it I will post it.


    Here is were I found the talk back info,http://www.sparkplugs.com/sparkplug411.asp?kw=Resistor&mfid=0
     
    Last edited: Jan 30, 2010
  3. Plan-b

    Plan-b ArboristSite Operative

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  4. Trigger Man

    Trigger Man Addicted to ArboristSite

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  5. CGC4200

    CGC4200 Addicted to ArboristSite

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    Resistor vs. non resistor plugs

    I had one local dealer say there was no difference. I have seen threads
    on AS from site sponsor dealers that non-resistor plugs can fry
    a ignition module. Why take the chance?
     
  6. Philbert

    Philbert Chainsaw Enthusiast

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    Thanks guys,

    I have heard people say that it only has to do with a radio, but the electronic ignition part is pretty interesting. This raises the complementary question: Is there ever an advantage to using a non-resistor plug (or why aren't all plugs now made to be the resistor type)?

    Philbert
     
  7. Tzed250

    Tzed250 Addicted to ArboristSite

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    .


    Most digital ignitions(newer saws)don't like the RF noise that non-resistor generate.


    .
     
  8. Plan-b

    Plan-b ArboristSite Operative

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    More so in a high output race application where RF is not an issue.


    Neither do pacemakers :chainsaw:
     
  9. CGC4200

    CGC4200 Addicted to ArboristSite

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    non resistor plugs should be OK with a point & condenser ignition

    Except for annoying neighbors with RF noise, why take the chance on frying
    ignition on newer saws? The resistor plugs are easier to find & much
    cheaper than a ignition module.
     
  10. Trigger Man

    Trigger Man Addicted to ArboristSite

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    :agree2: but some shops I've been to slap a non resistor plug on the counter and say there you go, When I tell them no I want the resistor plug they look at me funny, since then I have been buying my plugs from a hardware store. I hate :censored:shops that don't have a clue.
     
  11. 50:1

    50:1 ArboristSite Operative

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    how can you tell if a plug is a resistor or nonresistor plug?
     
  12. w8ye

    w8ye Addicted to ArboristSite

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    They have a "R" in their part number or you can measure with a OHM meter between the electrode center and the top of the plug
     
  13. 50:1

    50:1 ArboristSite Operative

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    so an r in the part/plug number always denotes that it's a resistor plug? thanks
     
  14. 3000 FPS

    3000 FPS Addicted to ArboristSite

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    So the bottom line according to the article that plan-b posted is the strength of the spark is not affected by the resistor in a resistor type plug and it does cut down on the amount of noise in the spark that can be reflected back into the primary of the coil and then to the electronic module itself and maybe causing damage. If it were me and my saw recommended a resistor plug that is what I would use.
     
    Last edited: Mar 28, 2012
  15. Sagetown

    Sagetown Farmer and a STIHL

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    Thanks for bringing that up Philbert. Not only are you a little wiser, I am too. :)
     

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