jetting an evo

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  • John.R
    John.R
    4 years ago
    I'm going to go through process of jetting my Evo again shortly.
    Currently running a 45 or 46 pilot, n65c sporty needle (with a .5mm shim), and a 170 main.

    Have a feeling the needle + shim is overfueling at partial throttle, while WOT is lacking slightly, so plan  is to bump up the main and take out the shim. Will update when main jets arrived, ordered a 175/180/185 
  • Tarvis
    Tarvis
    4 years ago
    quick update:
    Dropped the main jet back to a 175 from 180, left the 44 pilot in and took it for a good long ride on the weekend. Ran well, nice even power and if I wasn't having the fuelling issues i wouldn't think anything was wrong with it. Pulled the rear plug to find that half of the ceramic was black covered and the other half was a nice tan/off white colour. Not sure what to make of that so I'm going to leave it as is for a while and just take a set of plugs with me if I get in the shit.

    I'll keep updating on here just in case anyone is interested but if this takes much longer I might just cam the bike and start all over again!


  • tussuck
    tussuck
    4 years ago
    Quoting Tarvis on 21 Jan 2020 10:45 AM

    quick update:
    Dropped the main jet back to a 175 from 180, left the 44 pilot in and took it for a good long ride on the weekend. Ran well, nice even power and if I wasn't having the fuelling issues i wouldn't think anything was wrong with it. Pulled the rear plug to find that half of the ceramic was black covered and the other half was a nice tan/off white colour. Not sure what to make of that so I'm going to leave it as is for a while and just take a set of plugs with me if I get in the shit.

    I'll keep updating on here just in case anyone is interested but if this takes much longer I might just cam the bike and start all over again!


    you could look at altering the plugs and running a slightly hotter one which would help in the cleaning of the plug.  Oddly enough its not the actual colour of the end of the ceramic but rather the colour pattern and heat lines further down the ceramic towards the spark plug lead end.  
    Black on one side and tan the other is not that bad per-sec either as the stock combustion chamber "D" shape would supprot that observation.
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