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jetting chart for 440 polaris

This is a discussion on jetting chart for 440 polaris within the The Performance Tuning Shop forums, part of the Snowmobiles category; Does anyone know where I can find a chart showing the correct jets for different temperatures/altitudes for a 440 Fuji liquid cooled motor out of ...

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Thread: jetting chart for 440 polaris

  1. #1
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    Does anyone know where I can find a chart showing the correct jets for different temperatures/altitudes for a 440 Fuji liquid cooled motor out of a Polaris?

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    try looking under the hood on the sticker! this should give you the factory settings.
    a couple of things to keep in mind, first, aaltitude changes on the chart about every 3000 feet, decide where you ride, 0-3000, 3000+ etc.
    2nd, the larger the number on the jet, the more fuel it will let in, now as temps rise (30-40), you can lean (go down with the number) quite a bit, as the temperature goes down, to reduce the risk of a lean condition, you must jet up in size.
    to understand whats going on with yor fuel/air mixture, i'll try a simple explanation: smaller jet size, fuel and air are mixed together in a vortex as the the throttle is opened, more air,more fuel, etc, etc,.as the altitude and temp change, so does this fuel air mixture, as the temps drop, the fuel/air mixture needs to increase as the air is less dense and dryer as the temps fall, to keep from burning up an engine, these should be matched apropriately to the existing weather and or altitude conditions, too lean means that you are letting more air than fuel in, this will cause the cylinder walls to run hot and dry(not good!) if you do change jets, always keep in mind the temp and altitude, and if you get really serious about it you have to factor in the atmospheric pressure too! Mikuni sells a slide-rule type gauge for proper jetting in different conditions(well worth the 4 or 5 bucks)
    here is mikuni's website, find your carb there and it should help you; www.mikuni.com
    as always, rejet carefully, do a plug check!!! don't go up or down in too big of steps at once, go carefully!
    you didn't mention what type and size carbs you have but, the needle can be raised or lowered to change the leanness or richness of the jetting also to some extent.
    good luck, hope this helps you some, dave

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    NightTrain's Avatar
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    Quickest way to find that out is to call a Polaris dealer & ask for the shop, they'll tell you. Since you put that 440 in there, I would compare both charts and if they ARE different, remove the 500 chart and buy the 440 chart & install it... it's real handy to have that there with the machine & shouldn't cost more than a few bucks.
    Again, as I said in your other post, make sure you have the correct carb sizes - I don't know if the 440s and 500s came with the same size carbs. That's very important. The 440 is a good engine, but there's a big difference between the two of them in performance, and I think that would mostly be due to larger carbs & exhaust - even though there's only about 48cc difference in the displacement (the 500 is really a 488cc engine).

    Welcome to the Forum, by the way.

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    ripperd's Avatar
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    i'll go get pics of my hood, back in a bit

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    ripperd's Avatar
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    From a 1992 440 XCR motor (L/C)
    [img]/snofan/../images/users/ripperd2/jettingchart.jpg[/img]

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    Man, you guys are awesome, thanks for all the help! I wish I could get service like this from my dealer.

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