28 Responses

  1. jamie
    jamie at |
  2. Riderwww
    Riderwww at |

    Hi daniel, i had a Shitty spark plug on my polini Sport, equivalent with the NGK B9ES, the color of the spark plug was chocolate brown.
    Now, ive got a NGK BR9EIX iridium spark plug, and looks like it’s running too lean… WTF?

    Btw, the iridium spark plug will ensure better performance than standard spark plugs? More hp , more torque? Or just no difference?


  3. Riderwwwwwwwwwww
    Riderwwwwwwwwwww at |

    I ride the new spark for 5kms and now its chocolate brown, how good it is?

  4. ryou
    ryou at |

    Hey Dan!
    I was wondering if i change my air filter with K&N Cone with its Cotton based filter, will it make my engine too lean?

  5. Mahar183
    Mahar183 at |

    Hello Daniel , I have a Piaggio typhoon air cooled ,183 highly modified with pm Tuning expansion chamber 55mm crank , 34mm carb rd 350 reed valve , horse power ignition kit ,cylinder has also been heavily modified, ….. Setting the engine up !! I used the guide from your previous post about carb main jet settings , 34×5=170 … Still feels flat needle setting on the top clip , idle is also rich 50 pilot … My 1st thought is the main jet being rich is causing low end issues do you have a guide to doing idle jet aswell , I’ve turned the mixture screw all the way in and engine is still on does this mean main jet is too big or am I wrong

    Also I got a guide with the carb when I bought it and the settings they have give are

    42 slow jet
    142 main jet
    Jet needle setting 3
    The carb is a pwk34mm flatslide power jet but I’ve blocked it off

  6. Justin Berry
    Justin Berry at |

    I found this article looking through search of spark plug conditions. I don’t have a scooter I have a 8 cylinder truck and you are the only one I could understand in determining my plugs. Mine, by your description, were running lean. Anyway thanks for the article.

  7. Shaun Roberts
    Shaun Roberts at |

    you got your spark plug reading all wrong. please review. lean is optimal. vice versa.

    1. Timothy Seward
      Timothy Seward at |

      Yeah dude your picture is wrong…. your lean plug is supposed to be optimal.. optimal is brown not white.. you are going to be responsible for blowing up peoples top ends you dick

    2. Alan Day
      Alan Day at |

      Absolutely correct !!

  8. Laurence
    Laurence at |

    Pretty sure your plug labels are incorrect; the rich one is right but the lean and optimal should be swapped round… a lean mixture increases the heat of combustion and tends to glaze the ceramic of the spark plug and burn off any deposits that may have accumulated, leading to the very white, clean insulator on the right of the picture. The left plug looks to be optimal with a grey brown colour from the light deposits of a correctly adjusted mixture.

  9. murray
    murray at |

    yup pictures are the wrong way around,anything looking white is lean or hot,hopefully not too many people go by the pics

  10. John Hodges
    John Hodges at |

    Hey Timothy Seward
    Anyone can make a mistake so don’t be so objectionable by call the author a DICK.
    He shares his knowledge to us free of charge. Ok sometimes he gets it wrong but don’t be such a “plonker” about it. Suggest you shove your head back up your arse where it belongs.

  11. John
    John at |

    Hi just a quick one? My scooter is running to leaning running it on a 24mm carb 108 main jet it’s fine on tickover but when I take it for a run it looses power top end I’ve put a 150cc big bore on it any suggestions where I’m going wrong?

  12. mickey
    mickey at |

    Also there is a spec,setting,say from .06 mm.-.07 mm.or 24-28 in.I tried in so .either to rich or lean.What is best?

  13. RF Prescott
    RF Prescott at |

    Providing you have the correct heat range plug, base of insulator deep inside is read to check main jet. Tip of electrodes checks idle mixture adjustment and pilot jet with air screw 1 3/4 to 2 turns out from closed. Make runs also at 1/2 throttle to check needle position.

  14. mickey
    mickey at |

    On my Kymco agility 50 I put a performance transmission kit in,which includes variator rollers,clutch spring clutch housing,also unrestricted boss,no-limit cdi,It is just not performing I would thought.Spark pug it at 0.26in. new air filter and it is a 2017.I gonna try a 4 gm roller weight.If you have some suggestion,please.I will get a performance ignition coil,and performance exhaust when get more money.Thanks David.it is hard to find performance parts for the kymco agility 50,most are GY6

  15. FastGerman
    FastGerman at |

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  16. Barry L. Lopez
    Barry L. Lopez at |

    Thanks for sharing such an informative article. The spark plug is the essential thing of a vehicle. You described clearly about the maintenance system of it.it will be helpful for us.keep posting like this. :)

  17. Jude
    Jude at |

    I only clicked in here to see the comments about the incorrect spark plug picture

  18. Lee
    Lee at |

    According to Holley and other sites your plug pictures are wrong. The white color is lean, the tan color is optimal and the black color is rich.

    1. Lee
      Lee at |

      I have been building engines for cars, high performance, trucks, semi trucks, motorcycles ect. for over thirty five years. Your plug pics are wrong.

  19. Brett
    Brett at |

    How many times have I seem this? “loose”… I think you mean lose! It’s hard to take you seriously when you fail to have an understanding of basic grammar.
    Last paragraph-
    You might loose some power but you can ensure that your engine won’t be damaged during long full throttle trips under extreme conditions.


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