Indexing spark plugs

Discussion in 'Outboard Maintenance' started by Nick5288, Jun 19, 2015.

  1. Nick5288

    Nick5288 I Love microskiff.com!

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    I have a 2005 Yamaha 25 2 stroke. Motor runs perfect but has a little bit of a rough idle but clears with a little rpm change. My brother is a mechanic and has a etec and told me I need to index the plugs so the opening faces the exhaust port. He said it cleared his idle up. Anyone done this on a Yamaha 25?
     
  2. anytide

    anytide Administrator Staff Member

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    on a high HP 8 cylinder hot rod @ the dyno you mught notice a difference , but in a kicker outboard i doubt youll notice any improvement in idle.

    its a 2 stroke....... go fishing  :)


    :-?
     

  3. topnative2

    topnative2 Well-Known Member

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    https://www.youtube.com/watch?v=Hi658MThS9o

    indexing does tweak any motor......probably not a difference like anytide stated...can't hurt
     
  4. noeettica

    noeettica Well-Known Member

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    Crap ! Cat is out of the Bag ... LOL
     
  5. Brett

    Brett > PRO STAFF <

    H'mmmm, I think I've found a small problem with this concept [​IMG]


    how would you index a gapless plug? [​IMG]


    [​IMG]
     
  6. anytide

    anytide Administrator Staff Member

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  7. noeettica

    noeettica Well-Known Member

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    Funny thing ...

    2 Identical Mercs one has factory Gapless other does not wonder if plugs are :D interchangeable between the motors and why or why not ... :D
     
  8. Creek Runner

    Creek Runner Well-Known Member

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    Some indentical motors are not indentitcal when indentified with the seriel number, due to mid year model changes and where it was originally being shipped to. Example a 50 Mercury motor being shipped to Colorado, Canada, and florida would have had different jets, timming, and spark plugs due to the altitude of Colorado and the extreme cold temps of Canada, we use to have to rejet and set the timming on all the motors we use to get from Canada.

    All new direct injected two strokes, HPDi, Optimax, and Etechs all need to have their plugs indexed and yes it does make a big difference, a carbed or efi 2 stroke will see no benefit of indexing.

    Creek