How to Rejet your CRF150F for better power !
  • User avatar
    mustang
    Posts: 255
    Joined: Fri Jul 15, 2005 4:12 pm

    How to Rejet your CRF150F for better power !

    by mustang » Sun Apr 22, 2007 8:03 am

    The CRF150F comes from Honda very lean in the idle circuit and this makes starting a cold engine very difficult .
    The following change to the bike will give you a mild boost in power as well as a much better running 150F , that will start easier and actually IDLE without stalling .
    and it will only cost you about $40
    You will need the following items :

    -99103-KPT-0420-Slow jet (42 being the size, stock is 40)

    -99113-GHB-1150-Main jet (115 being the size, stock is 98 )

    A good hi flow air filter like a twin air or no toil or uni , etc , etc.

    You need to start by removing your seat from bike .

    1. Remove the rubber snorkel from airbox , just grab it and yank it off .

    2. Remove the baffle from the end of the exhaust pipe , drill a few 1/4 inch holes in the solid steel plate on the inside end and reinstall it in bike , Now it will breathe a little better and you will still have a quiet bike .

    3. unscrew the cap where the throttle cable goes in the top of carb .

    4. pull the cap and slide that is attached to the cable staight out .

    5. now you can change the needle , but you really don't have to change it just move the clip to the fourth notch from the top of the needle if it isn't already there at the fourth notch.

    6. unscrew the band clamp on the air boot at the rear of carb , remove the two 10mm nuts that hold the carb to the intake manifold .

    7. now you can remove the carb from bike (make sure to unhook the vent tube from the clip on the frame

    8. Turn carb upside down over a bucket and gas will drain out .

    9. remove the philips screws from the bottom of the carb on the float bowl , remove float bowl and you can now see the main jet and it has a little plastic pc. around it that has a notch in it for the pilot jet clearance

    10. replace the main jet and pilot (don't overly tighten or you will break them off in the carb body, not good)

    11. reassemble the reverse of above and you are done except for fine tuning the fuel screw after you get the bike running .

    12. Replace the air filter with a new one , like a twin air or no toil etc. don't use the sponge that honda sends with the bike

    you're gonna like the way it starts and runs now !
    c-ya****mustang Image
  • User avatar
    Cappy
    Posts: 5
    Joined: Sun May 21, 2006 7:51 am

    Jetting

    by Cappy » Wed Nov 21, 2007 5:57 pm

    Just rejetted my sons 2006 150F
    MOds:
    target altitude: 5000-7000ASL
    Open air box
    Twin Air filter
    Spark arrester back pressure plate removed
    Main Jet: 150
    Idle jet: 40
    air screw: 1 3/4 turns
    needle clip pos: top ring
    24 hours in a day, 24 beers in a case,
    Coincidence...I think NOT!
  • User avatar
    zak13
    Posts: 955
    Joined: Tue Apr 03, 2007 4:58 pm

    Re: Jetting

    by zak13 » Thu Nov 22, 2007 5:12 am

    Cappy wrote:Just rejetted my sons 2006 150F
    MOds:
    target altitude: 5000-7000ASL
    Open air box
    Twin Air filter
    Spark arrester back pressure plate removed
    Main Jet: 150
    Idle jet: 40
    air screw: 1 3/4 turns
    needle clip pos: top ring

    really
    wouldnt that make it run very lean
    sellin my xr100
    Image
  • User avatar
    Cappy
    Posts: 5
    Joined: Sun May 21, 2006 7:51 am

    by Cappy » Thu Nov 22, 2007 12:12 pm

    Well at anything under 5000' I'd say yes, but in a 5000-7000'ASL area it runs perfect with very little popping.
    24 hours in a day, 24 beers in a case,
    Coincidence...I think NOT!
  • User avatar
    Cappy
    Posts: 5
    Joined: Sun May 21, 2006 7:51 am

    by Cappy » Sat Nov 24, 2007 11:28 am

    OK...the 150 was a misprint, we were actually using a 130. However, it began to cut out on the top so reducing to a 42 idle jet and a 120 main cleaned it right up.
    24 hours in a day, 24 beers in a case,
    Coincidence...I think NOT!
  • User avatar
    zak13
    Posts: 955
    Joined: Tue Apr 03, 2007 4:58 pm

    by zak13 » Sat Nov 24, 2007 5:50 pm

    whered you get the 130 from
    sellin my xr100
    Image
  • User avatar
    Cappy
    Posts: 5
    Joined: Sun May 21, 2006 7:51 am

    by Cappy » Mon Nov 26, 2007 8:05 am

    I had it on hand from some other application but it is just a Keihn standard 130 main jet.
    24 hours in a day, 24 beers in a case,
    Coincidence...I think NOT!
  • T Man
    Posts: 6
    Joined: Mon Oct 13, 2008 8:03 pm

    by T Man » Thu Oct 30, 2008 8:46 pm

    I rejetted my sons 05 150f as suggested, and removed the air box snorkel. 115 mj and 42 pj. The bike has a pro circuit pipe.

    A friend suggested I should adjust the fuel mixture screw. Any suggestion for best setting?
  • User avatar
    mustang
    Posts: 255
    Joined: Fri Jul 15, 2005 4:12 pm

    by mustang » Fri Oct 31, 2008 5:52 am

    start at 1 1/2 turns and try opening it a little , you are looking for a "HAPPY " sounding idle speed
    c-ya****mustang Image
  • kpotratz
    Posts: 2
    Joined: Mon Mar 16, 2009 9:45 pm

    by kpotratz » Thu Mar 26, 2009 2:39 pm

    Mustang

    2008 crf 150
    Im @ 2000'
    temperature 50-70 F
    what would be the proper set up to do .

    Thanks
    Ken
    2007 crf 250X
    2008 crf 150F
    2006 crf 70
    2006 crf 50
    2006 crf 50
  • MOSPEED
    Posts: 4
    Joined: Thu Feb 09, 2006 8:17 pm

    by MOSPEED » Thu Jul 16, 2009 1:37 pm

    The power-up kit worked perfectly! My 150 starts instantly now. Thanks Mustang!
    06 Kawasaki ZX14
    05 Harley FXDL
    05 CRF450X
    05 CRF250X
    06 CRF150F
  • kyle7683
    Posts: 10
    Joined: Tue Aug 27, 2013 3:09 pm

    by kyle7683 » Sat Sep 07, 2013 7:43 pm

    What should the fuel screw be set to?mines at 3.5 turns out now and I still get some hesitation when full throttle applied at idle and while riding
  • saefabri
    Posts: 35
    Joined: Sat Feb 02, 2013 2:18 am

    by saefabri » Sun Sep 08, 2013 4:14 am

    I used the JD kit on 2013 CRF150RB
    Now bike starts easier
    No hang on idle
    Did not have to remove the carb though.
  • Cameron Clontz
    Posts: 1
    Joined: Sun Dec 03, 2017 6:41 pm

    Re: How to Rejet your CRF150F for better power !

    by Cameron Clontz » Sun Dec 03, 2017 6:44 pm

    If I just bought a 2004 Honda crf 150f and I want to put a pro circuit t4 full system what do I need for do to the air box and carb?

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