450 EXC Won't Idle

Discussion in 'Thumpers' started by De Eee, Sep 6, 2012.

  1. De Eee

    De Eee Been here awhile

    Joined:
    Mar 30, 2006
    Oddometer:
    172
    Location:
    20 miles from Santiago Pk.
    Hey y'all. My 450 EXC (07) that has always been easy to start has gotten hard starting. I have to use the choke and never did before.
    As well it doesn't idle like it used to. When it's warm and I rev it a bit the rpm drops off but then hesitates to return to idle.
    I thought maybe the return cable was binding or broken.
    Time to clean carb?
    Idle jet?
    #1
  2. Gunslinger1

    Gunslinger1 GIVE'R

    Joined:
    Aug 22, 2006
    Oddometer:
    637
    Location:
    Rolla, MO
    If the bike has been sitting with gas in the carb the pilot is probably congested..........it's easy to ck there first.
    #2
  3. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    8,475
    Stock jetting? If so yourself a favor and install a JD jet kit while you are in there. Sounds like a partially clogged pilot jet but stock they are super lean already stock. The JD needle smooths the transitions between circuits and really brings the response up.
    #3
  4. clapped_r6

    clapped_r6 The Spoad Warrior

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    Jan 3, 2006
    Oddometer:
    2,741
    Location:
    Ridgefield, WA
    +1 sounds lean, you're on the right track. probably pilot.
    #4
  5. crazybrit

    crazybrit Long timer

    Joined:
    Mar 16, 2006
    Oddometer:
    8,556
    Location:
    Portland, OR
    The JD kit for the RFS is massively overrated IMO. The needle is too rich.

    If you feel you need to reject, buy some jets from jetsrus and contact DJH on ktmtalk for his needle.

    However, since it used to run well I would suggest you ignore those telling you to install X, Y and Z and instead ........
    #5
  6. Off the grid

    Off the grid Seeker of the Unf

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    Oddometer:
    11,716
    Location:
    That buzzing in your earhole, NorCal.
    Check your breather hoses too. Shouldn't be too hard to diagnose.
    #6
  7. Brute

    Brute Melbourne , outer east .

    Joined:
    Dec 6, 2007
    Oddometer:
    1,076
    Check your valve clearances .
    #7
  8. husqvarna

    husqvarna Been here awhile

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    May 29, 2007
    Oddometer:
    143
    Location:
    Darkest Efrika
    I had a 525 that behaved in a similar way. Cleaned the carb multiple times. Eventually traced (by my local friendly mechanic; not me) to a bad spark plug cap; even though the plug sparked ok when checked. But check the plug as well.
    #8
  9. Navin

    Navin Long timer

    Joined:
    Sep 22, 2009
    Oddometer:
    8,475
    If you just bolt it in and go it might not be as good as it can get. I find an hour of testing and tune yielded huge results on every bike i used those needles on, 520exc, 525SX a few Huskys and my most recent 505 and 530.The smoothness as the carb goes thru its circuits is far better to me than any stock needle.
    #9
  10. De Eee

    De Eee Been here awhile

    Joined:
    Mar 30, 2006
    Oddometer:
    172
    Location:
    20 miles from Santiago Pk.
    Yo, the JD kit took care of it. Nice power improvement as well.
    #10