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Hey re-jet veterans. I need advice

Discussion in 'XJ Modifications' started by psan, May 20, 2011.

  1. psan

    psan New Member

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    Hey all, i recently put a 6.5 inch K&N filter on my surge tank and a mini K&N on the turbo to my 1983 seca turbo. After this it is however running lean. I have not rejet a bike before but am willing to learn. From what i understand the installation of the carb parts isnt the hard part, its the carb syncing and finding the correct jet size. I went through Chacal's guidelines to rejetting and this is what i figured out. Just a side note, where i am is 1343 feet above sea level

    Mikuni Carbs are on my bike

    Main Jet
    +4 main fuel jet sizes for individual pod filters (no airbox)

    Old jet size cylindar 1&4 #127.5

    Old jet size cylindar 2&3 #132.5

    New jet size cylindar 1&4 #129.5

    New jet size cylindar 2&3 #134.5

    HCP6933 Aftermarket Mikuni MAIN FUEL JET #130 (size i am thinking of buying)

    HCP6934 Aftermarket Mikuni MAIN FUEL JET #135 (size i am thinking of buying)

    PILOT FUEL JET
    Increase the pilot fuel jet size +1 for every +3 main fuel jet size increases.

    Old jet size for all cylindars #32.5

    New jet size: stay the same?

    Needle? I have no idea what needle size i need or if need to change? help on this part

    This is how i came to what size jets to buy.

    MAIN FUEL JET SIZE CHANGES NEEDED PER TYPICAL MODIFICATION:

    Typical Intake Changes:

    +2 main fuel jet sizes for single K&N filter (inside a stock airbox)

    or

    +2 main fuel jet size for drilling holes in the airbox with stock filter

    or

    +4 main fuel jet sizes for individual pod filters (no airbox)

    PILOT FUEL JET SIZES CHANGES NEEDED PER TYPICAL MODIFICATION:

    Pilot fuel jet size changes are related only to the change in main fuel jet sizes according to the main fuel jet size formula described above. Note that this pilot fuel jet rule is for the main fuel jet size change BEFORE any main fuel jet altitude compensation is factored in:

    Increase the pilot fuel jet size +1 for every +3 main fuel jet size increases.

    - Decrease pilot fuel jet size by 1 for every 6000' above sea level.

    Additional changes:

    - Add up all the main fuel jet size increases and subtract 2 sizes.

    - Decrease main fuel jet size by 2 sizes per every 2000' above sea level.

    - Under a mis-match condition, such as when using pod filters with a 100% stock exhaust, or 4-into-1 header with stock filter and air box, then subtract 2 main fuel jet sizes.

    Is there anything else i am missing? Thanks for everyones help. This will be my first re-jetting job. So i need all the help i can get
     

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