Jetting database for Honda CRF's
  • Thor515
    Posts: 1
    Joined: Tue Nov 27, 2007 8:56 pm

    by Thor515 » Thu Feb 07, 2008 10:14 pm

    Model: 05 CRF250R
    Settings for what altitude: 2700 ft
    Main jet size: 175
    Needle used: Stock
    clip location: 3rd
    Airbox mods: Blocked Off, pink tube eliminated
    Air Filter changes: Twin Air filter and cage (screen eliminated)
    Any other related changes:
    1) U4.2 race fuel
    2) FMF Pipe and Factory 4 muffler
    3) 55 Leak Jet (replaced stock 70)
    4) Boyesen Quick Shot 2
    5) Power Now System
    6) Fuel Screw out 1.5 turns
    7) Pilot/Slow Jet Stock (42)
  • User avatar
    jake2
    Posts: 5
    Joined: Tue May 20, 2008 3:53 am

    by jake2 » Fri Jul 18, 2008 10:28 pm

    Model: 2007 250X
    Settings for what altitude: 2 turns out at 142 ft or 43 metres.
    Main jet size: 170.
    Pilot size: 42 Standard.
    Needle used: Stock.
    Clip location: 3rd from top.
    Airbox mods: Cut open at top only.
    Air Filter changes: Stock filter & cage
    Any other related changes: FMF Q4 slip on + stock header.
  • User avatar
    speedilad
    Posts: 4
    Joined: Tue Sep 20, 2005 10:12 am

    by speedilad » Wed Sep 03, 2008 10:01 am

    2005 crf450x

    air box mod - left and right as per JD Jetting

    home altitude less than 1,000 ft
    main 165
    red JD needle 4th from top

    Colorado greater than 9,000 ft
    main 155
    red JD needle 3rd from top

    these settings run great at each altitude
  • User avatar
    sand.man
    Posts: 442
    Joined: Tue Apr 22, 2008 11:04 am

    by sand.man » Mon Sep 22, 2008 8:28 pm

    Year: 2003 450R
    Elevation: Sea level - 100M
    Temperature Range: 5c - 30c
    Backfire Screen: N/A
    Air Filter: Stock
    Slow jet: 45
    Main Jet: 180
    Needle: JB Red
    Needle Clip Position: #6
    Fuel Screw Type: Stock
    Fuel Screw Setting: 1 3/4 Out
    AP Modified: Yes, rivet ground and o-ring
    Leak Jet: 55
    AP Cover: Stock
    Exhaust Type: Jardine RT-4 slip-on
    Exhaust Modified: No
  • AgentRookie
    Posts: 4
    Joined: Tue Mar 03, 2009 4:29 am

    Re: Jetting data base for crf's

    by AgentRookie » Thu Mar 12, 2009 1:17 pm

    Model: CRF 250 R 2009
    Settings for what altitude: nnnnn ft
    Main jet size: #185
    Needle used: Blue JD-Kit
    clip location: 6th
    Airbox mods: stock
    Air Filter changes: stock
    Any other related changes: stock
  • dobent4@yahoo.com
    Posts: 5039
    Joined: Sun Aug 14, 2005 6:21 pm

    by dobent4@yahoo.com » Fri Mar 13, 2009 2:37 am

    2005 crf450x
    air box mod - left and right as per JD Jetting
    home altitude less than 1,000 ft
    main 165
    red JD needle 4th from top
    Colorado greater than 9,000 ft
    main 155
    red JD needle 3rd from top
    these settings run great at each altitude

    Thank you,
    We can use more high altitude settings and appeciate it.
    JD's got it down, don't they?
    He actually tests every bike he sells kits for at altitude,the 450X he posed with in Coloreado somwhere in a photo next to a 13,000(!) foot sign. Wow.
    So he just had you reduce the main to a 155 and one click leaner on the needle.
    Excellent, I'll bet it runs great. Doug
  • staticbags
    Posts: 22
    Joined: Thu Feb 28, 2008 8:35 am

    help jetting at altitude

    by staticbags » Tue Jun 16, 2009 6:04 pm

    ok, i need help to rejet for trip to Co. (durango - Telluride) riding 9000 to 13000 feet. I think mostly 9k to 11k feet. We have 2 250X bikes
    both have airbox cut open, screen removed, twin air filters.
    one has 250r pipe(love it) other has FMF pipe
    I have a jd jet kit and don't know whats in other bike.

    I need to rejet both bikes for our ride next weekend.
    any help appreciated. I am going out now to read JD instructions, but would like any and all feedback i can get from you guys.
    jeff
    austin tx
  • User avatar
    paul turner
    Posts: 7578
    Joined: Thu Sep 22, 2005 9:03 pm

    by paul turner » Tue Jun 16, 2009 7:50 pm

    Both bike should be set up per JD's instructions. If you know that the temps at Colorado are gonna be fair, then follow his setup for warm weather/mid altitude jetting, i.e. Red Needle and recommended clip position which is usually 4th clip from top.
    Both bikes are opened up I presume, so the really need 42 pilot jets.
    It is imperative that both bikes have aftermarket fuel screws installed, this alone will be the single most important part of a good running bike versus a bad day.
    To adjust your fuel screw at altitude, warm the bike well, almost normal hot. Run the fuel screw in 1/8 turn and each time rev the bike, when the bike just develops a deccel pop, run the screw out 1/8 turn, maybe 1/4. this is the optimum idle/off idle mix. Now adjust the idle to what your ear thinks is 1500-1700rpms, now you're ready to ride. If during the ride you increase elevation and experience the idle/off idle getting slightly fat, then bike dies, run the fuel screw in a bit till the idle comes back to what your ear likes from previous setting.

    Have a great trip. :)


    paul
    If you ain't crashin', you ain't ridin' :-)
    Image
  • staticbags
    Posts: 22
    Joined: Thu Feb 28, 2008 8:35 am

    thanks paul

    by staticbags » Tue Jun 16, 2009 9:47 pm

    thats the kind of info i need. both bikes do have aftermarket fuel /air screws. I did not mess with that last time i went to co. I know my bike does not have 42 pilot and i have a manual and still dont know exactly where that screw is to change it. I have the JD 42 in my kit, but not installed. I have rejetted couple times changing red needle clip pos. and main jet to 165 for sea level riding and bikes runs good but not perfect. has a little bog.
    when i last went to Co, i moved clip on red needle but don't remember where and i put in 155 main. I followed advice from experienced guys on here and it was little diff than jd's, but not much. bike had bog up there bad... i was not able to "pop" throttle and pull front wheel over water puddles like i wanted to. besides the bog, it ran great but Bog pissed me off and made me fall foward on bike many times expecting to pullup wheel but nothing.. I hope i can eliminate that this time.
    I only have 1 jd jet kit so will have to do best i can withthis new/used 05 bike i just purchased to take up there for a friend. (mine is 06)
    my direct email is jeff@hightechpackaging.com
    thanks again for your help.

    edit: found this in how to section.. finally an answer i have been looking for The slow jet is also referred to the pilot jet
  • User avatar
    acguy
    Posts: 6
    Joined: Tue Nov 09, 2004 11:16 am

    easy beginner setup

    by acguy » Fri Oct 30, 2009 4:36 pm

    This ran really well in Georgia (1000 ft) for a stock pipe on 2006 CRF250X.


    Stock pipe.
    Pulled diffuser - drilled about (20) 5/32" holes in the diffuser baffle end - reinstalled.
    Removed the snorkel lid.
    replaced 40 with 42 pilot
    replaced 130 with 142 main
    Fuel screw at 1 3/4 turns.

    Easy and cheap first mod setup, and runs crisp with lots of pull. Starts much quicker too.
    06 CRF250X
    Rekluse Z Start
  • dobent4@yahoo.com
    Posts: 5039
    Joined: Sun Aug 14, 2005 6:21 pm

    by dobent4@yahoo.com » Fri Oct 30, 2009 4:49 pm

    You're on the right track.
    In the end motors are just pumps, and if you can give the motor more air, more fuel, and it can process that efficiently (your plug will tell you in addition to the grin on your face :lol: ) you're going to love the results.
    It'll run even better with a JD needle and a 158-162 main jet.
    Though not quite as strong as the above it'll still run better if you put the needle clip down a space or two from where it comes stock.
    The needle effacts more of the rpm range than any other circuit. Doug
  • jhawk14200
    Posts: 19
    Joined: Wed Feb 03, 2010 7:46 am

    by jhawk14200 » Tue Mar 16, 2010 2:32 pm

    Model: 250X
    Settings for what altitude: 0-1000
    Main jet size: 160
    Needle used: Red JD kit
    clip location: 5th
    pilot jet: 42
    Airbox mods: cut open
    Air Filter changes:stock
    Any other related changes: drilled exhaust baffle

    Just did all this. What a difference over stock! Easy to start, and really brought this bike to life!
    2005 CRF250X Jd kit, 160 Main, 42 Pilot, CRFSONLY fuel screw 1 1/2 turns out, exhaust drilled, airbox mod.

    2004 CRF70F
    2008 CRF80F
    2006 CRF100F
    2005 CRF150F
  • dobent4@yahoo.com
    Posts: 5039
    Joined: Sun Aug 14, 2005 6:21 pm

    by dobent4@yahoo.com » Wed Mar 17, 2010 2:09 am

    That's how that "little trail bike" keeps winning shoot-outs, races, and will be known as an all -time classic before it's run is over. 7 years now for both X bikes, 7. Neither is anywhere near obsolete, far ,far from it.
    Just with a little tlc they turn into top shelf high performance off-roaders competitive with anything, yet you can still putt around at walking speed all day without a protest. Pretty impressive. Doug
  • User avatar
    belltownjefe
    Posts: 47
    Joined: Sat Mar 07, 2009 8:22 am

    by belltownjefe » Wed Mar 17, 2010 7:16 am

    Year: 2008 450X
    Elevation: 4000+/-
    Temperature Range: 40* - 100*
    Smog (AIS): Applied Racing Block Off Kit
    Airbox Modified Top: Yes
    Airbox Modified Sides: No
    Backfire Screen: Removed
    Air Filter: Stock
    Pilot Jet: 45
    Main Jet: 170
    Needle: NGGQ (2005 stock R needle)
    Needle Clip Position: 4th
    Fuel Screw Type: Zipty
    Fuel Screw Setting: 2 Turns Out
    AP Modified: No
    Leak Jet: 65
    AP Cover: Stock
    Exhaust Type: XR's Only Gen II Full System
    Exhaust Modified:
    Pink Wire Modified: Yes
  • gator
    Posts: 15
    Joined: Mon Jul 26, 2010 10:36 am

    by gator » Mon Sep 27, 2010 9:12 pm

    Settings reborn

    05 450X - Canadian
    1200 ft
    NCVS needle 3rd position
    165 Main
    42 Pilot
    Boyesen AP
    Snorkel removed
    Stock filter/cage/backfire screen
    Stock Exhaust, baffle removed
    Fuel screw 2 turns out

    Initially removed backfire screen, cut out sides and drilled several holes in top of airbox along with the above noted snorkel removal/jetting and exhaust mods. Way too much air! No fuel screw adjustment could correct the bog/backfire. Covered holes in top of airbox with tape...still too much...covered side holes...a little too much...replaced backfire screen - Perfect. Can anyone comment on this irregularity? Or is this irregular? Am I missing the mark at this elevation? The bike starts and runs great with lots of power, little to no popping on decel, great throttle response. Can I make it better?
    "Its better to burn out than fade away"

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