HOW TO: Rejetting your CRF150F for better power !
  • User avatar
    jspd234
    Posts: 52
    Joined: Wed Dec 14, 2005 9:34 pm

    D screw?

    by jspd234 » Fri Dec 16, 2011 9:01 pm

    so i ordered a 42 pilot, 115 main and the full power needle today. my wifes 2008 150f is completely stock. i will pull the airbox snorkel off, remove the silencer baffle and drill a few 1/4" holes in the proper area. do i need to get the tool to remove or adjust the D screw? thanks to everyone!!
    09 crf450x
    02 crf450r(sold) sniff..sniff! i'll miss u!
    05 drz110 for the kid
    08 crf150f for the wife
    ASC stockcar #34
    10 wins 35 podiums and the 2007 ASC Racing Champion
  • User avatar
    jspd234
    Posts: 52
    Joined: Wed Dec 14, 2005 9:34 pm

    by jspd234 » Wed Jan 04, 2012 4:04 pm

    installed 42 pilot, 115 main, full power needle kit, pulled of airbox snorkel, drilled several holes in exhaust insert. starts easier, runs better,has more power, etc. it has a bog if you try to snap throttle open real fast from dead idle. if i twist the throttle a bit slower, it revs up fine. any ideas? i was thinking maybe go to a 108 main?
    09 crf450x
    02 crf450r(sold) sniff..sniff! i'll miss u!
    05 drz110 for the kid
    08 crf150f for the wife
    ASC stockcar #34
    10 wins 35 podiums and the 2007 ASC Racing Champion
  • User avatar
    crfsonly
    Owner
    Posts: 9639
    Joined: Thu Apr 01, 2004 3:45 pm

    by crfsonly » Wed Jan 04, 2012 4:11 pm

    off idle bog is the pilot circuit. check your fuel screw and make sure it's at least 1 3/4 open. you can open it up to 2 turns out. if this doesn't help then go up toe a 45 pilot.

    ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
    _________________
    CRF Parts and Accessories: http://crfsonly.com
  • User avatar
    jspd234
    Posts: 52
    Joined: Wed Dec 14, 2005 9:34 pm

    by jspd234 » Wed Jan 04, 2012 5:51 pm

    ordered d shaped fuel screw bit AND new fuel screw from you yesterday so i will try it once i install it and report back the results. thanks!
    09 crf450x
    02 crf450r(sold) sniff..sniff! i'll miss u!
    05 drz110 for the kid
    08 crf150f for the wife
    ASC stockcar #34
    10 wins 35 podiums and the 2007 ASC Racing Champion
  • User avatar
    jspd234
    Posts: 52
    Joined: Wed Dec 14, 2005 9:34 pm

    by jspd234 » Sun Jan 08, 2012 9:48 pm

    removed d shaped fuel screw and installed adjustable fuel screw. its better but still has a slight bog still. ordered 45 pilot. waiting for it.
    09 crf450x
    02 crf450r(sold) sniff..sniff! i'll miss u!
    05 drz110 for the kid
    08 crf150f for the wife
    ASC stockcar #34
    10 wins 35 podiums and the 2007 ASC Racing Champion
  • james webb
    Posts: 1
    Joined: Sat Apr 07, 2012 4:56 am

    by james webb » Sat Apr 07, 2012 5:03 am

    if i change my main jet on my crf150f to a 115# does that mean i have to change my pilot at all?
  • User avatar
    HitsOutdoors
    Posts: 38
    Joined: Mon May 28, 2012 8:24 pm

    by HitsOutdoors » Mon Jun 25, 2012 9:34 pm

    jspd234 wrote:removed d shaped fuel screw and installed adjustable fuel screw. its better but still has a slight bog still. ordered 45 pilot. waiting for it.


    Im curious to hear how you made out. Im considering doing the rejetting to my boys 2012 150F but Im reading a bunch of mixed reviews on this thread about how the results went..
    Tom Heatley Jr

    2012 CRF 450X
    Rekluse Core EXP
    JD Jet kit
    R&D flex jet
    Air box Mod
    Stock muffler mod
  • Local Yokel
    Posts: 6
    Joined: Fri Jun 22, 2012 10:24 am

    by Local Yokel » Thu Jun 28, 2012 5:35 pm

    I too am wondering how this turned out. Also I haven't got a clue were this fuel screw with the D shaped head is??? Our 150F is a 2007.
  • Local Yokel
    Posts: 6
    Joined: Fri Jun 22, 2012 10:24 am

    by Local Yokel » Fri Jul 27, 2012 11:03 am

    CRF's only can count me as another satisfied customer.

    I just put in the 42 pilot, 108 main and replaced the fuel screw. My daughter's bike runs much better now.

    The fuel screw allowed me to really get it to idle nice. With excellent throttle response right off idle. Not sure how the spark plug will look after riding a bit..but we'll see. At that point, maybe I'll try the 115 main that was included in the power up kit.....

    I also bought the needle but decided that I would be introducing too many variables at once and did not install it. The bike runs great so I am reluctant to put it in. (It only helps the idle circuit..right?)

    I like this little bike better now. Being without a bike I wouldn't mind it if it was my own.

    That's all I've got for now.

    Justin
  • User avatar
    crfsonly
    Owner
    Posts: 9639
    Joined: Thu Apr 01, 2004 3:45 pm

    by crfsonly » Fri Jul 27, 2012 11:26 am

    excellent news. try the needle...it will help everywhere. pretty quick to install so definitely worth the effort.

    ken
    OEM Parts for Honda - Yamaha - Suzuki - Kawasaki: http://yeltrik.com
    _________________
    CRF Parts and Accessories: http://crfsonly.com
  • User avatar
    HitsOutdoors
    Posts: 38
    Joined: Mon May 28, 2012 8:24 pm

    by HitsOutdoors » Fri Jul 27, 2012 3:59 pm

    Alrighty, You got me headed over to look the kit up now..
    Tom Heatley Jr

    2012 CRF 450X
    Rekluse Core EXP
    JD Jet kit
    R&D flex jet
    Air box Mod
    Stock muffler mod
  • User avatar
    HitsOutdoors
    Posts: 38
    Joined: Mon May 28, 2012 8:24 pm

    by HitsOutdoors » Fri Jul 27, 2012 4:44 pm

    Just ordered the power up Kit and CRFs only Fuel screw. Will installing the 115 jet instead of the 108 have any negatives effects during moderate trail riding on this bike? Id like to get him as much snap out of this thing as I can but dont want any issues from overjetting.

    Thanks
    Tom Heatley Jr

    2012 CRF 450X
    Rekluse Core EXP
    JD Jet kit
    R&D flex jet
    Air box Mod
    Stock muffler mod
  • User avatar
    HitsOutdoors
    Posts: 38
    Joined: Mon May 28, 2012 8:24 pm

    An FYI on the 150F Power Up Kit

    by HitsOutdoors » Sat Oct 13, 2012 10:16 pm

    I finally got home from working in Houston and tonight I took the time to install the kit I purchased a month or so ago. First off. This kit is AWESOME for the 150F. Its a noticable increase in power and response as well as a smooth idle. I put the 115-42 combo in Jacobs 2012. The Roll pin handle on the CRFs Only Idle Mix screw hits the bowl once installed on the 2012. But that's nothing a quick pass or two across the roll pin with a grinder didn't fix. Just so everyone who is wondering knows. You ABSOLUTE MUST use the 42 pilot jet when jetting up the main jetting. Initially I went up to the 40 with the 108 jet and I could not get the bike to idle right. It tended to run on then after 5-10 seconds it would drop low and stall. I took it back apart and put the 42 in and everything was perfect with the air/fuel screw out 1 3/4 turns. Then I went ahead and put the 115 main jet in. Good luck to any of you folks out there who decide to buy the kit. It really makes the bike a power house for what it is..
    Tom Heatley Jr

    2012 CRF 450X
    Rekluse Core EXP
    JD Jet kit
    R&D flex jet
    Air box Mod
    Stock muffler mod
  • User avatar
    Kiwi
    Posts: 363
    Joined: Thu Sep 25, 2008 12:22 pm

    by Kiwi » Fri Jun 07, 2013 11:34 am

    dave611 wrote:tried this set up and it falls on its face at mid throttle and the plug gets dirty real quick. should i try a smaller main jet ???


    After doing the jetting mods, you have to re-adjust the fuel screw.

    On my 150F I did the jetting updates and it had an evil bog like you are experiencing. Then I adjusted the fuel screw and the bike ran great.
    2007 CRF450X with modified airbox, Uni filter w/no backfire screen, NCVS needle on 4th, 172 main, CRFs fuel screw at 2, Boyesen QS3, stock smog, 450R cam, FMF Megabomb header, Pro Circuit T-4 muffler, Pro Taper Evo bars, AS suspension
  • QuietMike
    Posts: 6
    Joined: Sun Sep 17, 2017 9:08 pm

    Re: HOW TO: Rejetting your CRF150F for better power !

    by QuietMike » Wed Sep 27, 2017 8:47 pm

    I just recently got an 03 150f, and after seeing this sticky and videos i noticed that my bike already was missing the muffler diffuser and the intake box restrictor - so i wanted to see if it was also rejetted,
    i found that the needle on the slide was in the 4th from the top position, and i found that the main jet has a little symbol, like a star? and the number 115 and the pilot jet has the same symbol and says 40S

    so i guess its been upgraded, but shouldn't the pilot jet be a 42?

Who is online

Users browsing this forum: No registered users and 1 guest