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JD Jet Kit( mainjet?)
  • DocCRF-X250
    Posts:70
    Joined:Fri Mar 09, 2007 2:40 pm
    JD Jet Kit( mainjet?)

    by DocCRF-X250 » Thu Nov 15, 2007 6:03 pm

    I just got my JD jet kit and was wondering what I should go with for my main? I heard from ~ awhile back that I should go with the 162 main, 42 pilot red needle in 5th clip and do AP mod. Only problem is that I got a 160, 165 main just wondering if anyone had an idea of which to use I'm thinking 165? I have done air box mod and baffle removed

    I have a '04 250 -x
    Thanks guys
  • Asmith
    Posts:14381
    Joined:Mon Apr 10, 2006 7:52 am

    by Asmith » Thu Nov 15, 2007 6:30 pm

    We are running a 158 in ours, so given your choices I would start with the 160. If it feels a little flat, bump up.
  • DocCRF-X250
    Posts:70
    Joined:Fri Mar 09, 2007 2:40 pm

    by DocCRF-X250 » Thu Nov 15, 2007 6:49 pm

    ~ do you think the 42 main and red needle 5th clip will still be good? AP mod as well
  • Asmith
    Posts:14381
    Joined:Mon Apr 10, 2006 7:52 am

    by Asmith » Thu Nov 15, 2007 7:38 pm

    DocCRF-X250 wrote:~ do you think the 42 main and red needle 5th clip will still be good? AP mod as well


    Yes to all.
  • rob_wiggins
    Posts:189
    Joined:Wed Oct 24, 2007 7:07 pm

    by rob_wiggins » Thu Nov 15, 2007 7:51 pm

    what the hell is jettin? I have been reading all the threads and as far as i can tell it is the way your bike breaths, which is important at altitude?
    We take risks not to escape life, but to keep life from escaping us.
  • Asmith
    Posts:14381
    Joined:Mon Apr 10, 2006 7:52 am

    by Asmith » Thu Nov 15, 2007 8:19 pm

    rob_wiggins wrote:what the hell is jettin? I have been reading all the threads and as far as i can tell it is the way your bike breaths, which is important at altitude?


    In a nutshell, it's the combination of the jets (orifices thru which the fuel passes)
    the needle shape, and the position of the clip on the needle.

    It's a delicate balance trying to provide an ideal mixture of air to fuel.

    Gasoline likes to burn at a ratio of 14.7:1 ( this is known as the Stoichiometric air-fuel ratio ).

    More gasoline lowers the ratio, less gasoline raises the ratio.
    Above 17:1 it is too lean to burn effectively, below 14:1 it is too rich to burn effectively.

    Since each part controls a different part of the throttle,
    they must be adjusted separately to work in harmony with each other.

    The pilot jet controls fuel from idle to 1/4 throttle.

    The needle jet controls fuel from 1/4 throttle to 3/4 throttle.

    The main jet controls fuel from 1/2 throttle to WFO.

    The AP ( Accelerator Pump ) shoots a small shot of fuel during rapid twisting of the throttle to aid in the increase of RPMs in a smooth manner.
    Too much will cause bog and too little causes bog.

    That was a big nutshell...
  • [email protected]
    Posts:5039
    Joined:Sun Aug 14, 2005 6:21 pm

    by [email protected] » Fri Nov 16, 2007 5:51 am

    AS,
    You sure have a lot of endorphins or SOMETHING going on with that brain of yours.
    I would have bet a million bucks that I wouldn't hear or read "Stoichiometric air-fuel ratio" today.....
    I wonder how long ago that theory was arrived at,anyhow. It still applies that's for sure.
    You are loved and appreciated, crazy or not :lol:
    Doug
  • Asmith
    Posts:14381
    Joined:Mon Apr 10, 2006 7:52 am

    by Asmith » Fri Nov 16, 2007 5:53 am

    PG will have me committed someday... :shock:
  • [email protected]
    Posts:5039
    Joined:Sun Aug 14, 2005 6:21 pm

    by [email protected] » Fri Nov 16, 2007 5:58 am

    From the highly recommended (by me) movie "Escape from New York"...
    "It's a great day to be young and insane".
    Well, insane anyway in my own case. Doug
  • Asmith
    Posts:14381
    Joined:Mon Apr 10, 2006 7:52 am

    by Asmith » Fri Nov 16, 2007 6:00 am

    [email protected] wrote:From the highly recommended (by me) movie "Escape from New York"...
    "It's a great day to be young and insane".
    Well, insane anyway in my own case. Doug


    :lol: :lol: :lol:
  • Contract
    Posts:3
    Joined:Wed Dec 05, 2007 1:41 am

    by Contract » Wed Dec 05, 2007 2:16 am

    What should the fuel screw be at for this setup? I've got a 160 main 42 pilot red needle with the airbox mod and baffle at 1000ft.
  • Asmith
    Posts:14381
    Joined:Mon Apr 10, 2006 7:52 am

    by Asmith » Wed Dec 05, 2007 6:42 am

    Contract wrote:What should the fuel screw be at for this setup? I've got a 160 main 42 pilot red needle with the airbox mod and baffle at 1000ft.


    About 2 turns out.
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