Motorcycle Club » Star 1100 Classic & Custom

When to re-jet?

6 posts from 4 voices
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  1. mgzbrz

    So I am putting on pipes and intake this spring. I will not be doing the intake install/jetting. My question is that I have heard of waiting to do re-jetting until it gets to be around the temperature that you are going to be riding in. Is there any truth to this, or could I rejet before the riding season gets in full season? Have any of you had problems with off season rejetting?


  2. khunder102

    Nah, no need to wait on the re-jet until the "appropriate" weather. Operating temperature is operating temperature, whatever the ambient is. It's my understanding that jetting and PMS settings may vary somewhat with altitude, but if that's not a concern, go ahead and have it done now. Remember, carburetors aren't all that precise anyway, and the bike will run a bit differently day to day depending on ambient temperature and humidity. Can't be helped.


  3. KinkSdar

    If you do just and intake modification, should you re-jet?
    Perhaps a half jet?

  4. wzdartan

    Try giving this a read.

  5. KinkSdar

    Try giving this a
    Interesting, still confused though. Sounds like I could keep my stock needles but add .05mm (2 shim) to them.
    But will need new pilots and mains and maybe a PMS.

    Well I guess that gives me something to look into and cost.

  6. wzdartan

    What you do to your carbs will depend strictly on what you do to the exhaust and the intake. You should change the jetting if you change either of these from stock. The principal is fairly simple... If you change the volume of air that is flowing through the motor without rejetting, it will change the air to fuel ratio. This ratio needs to be kept within a certain parameter. More air without a rejet = lean fuel. Larger jets installed during a rejet will correct this situation. Changing the intake or the exhaust from stock will allow more air to flow through the motor. Re jetting brings the air to fuel ratio back to where it belongs.


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