08 CRF450X jetting?
  • jsnotech
    Posts:90
    Joined:Mon Mar 16, 2009 12:45 pm
    08 CRF450X jetting?

    by jsnotech » Mon Mar 16, 2009 1:12 pm

    Yep, just got off the CR500 and moving onto a 450X. I bought a new 08 and I've read about cutting the air box. I ride at 5000'-7500' elevation and from 40-95 degrees. Nevada is dry and open like SoCal.

    So how about the Carb? (stock is FCR13B)
    -Main jet size (stock is #145)
    -Needle size (stock is NNEU) does this Needle from a 04' CRF450R work here also?
    -Clip position (clip position fixed this year?)
    -Slow/pilot jet (stock is#45)

    Thanks for responding! I'll miss that oil burner :cry:
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    Skoot22
    Posts:2380
    Joined:Sun Sep 03, 2006 9:51 pm

    by Skoot22 » Mon Mar 16, 2009 2:02 pm

    stock pilot is fine.
    165 main jet
    Yes the 04 450R needle will work great. For your elevation put in 3rd pos.
    Part # NCVS 16233-MEN-671
    I believe the 08 has a fixed Fuel Screw as well. So an aftermarket one will be needed. Look into the Crf's Only fuel screw. Its in the Catalog here online.

    Welcome to the site.
    Scott
    05 CRF450X
    Bakersfield, Ca
    Image
  • jsnotech
    Posts:90
    Joined:Mon Mar 16, 2009 12:45 pm

    by jsnotech » Wed Mar 18, 2009 10:21 pm

    thanks. what i have learned lately is...

    -stock, sea level is good with no intake or exhaust mods. Maybe for break in period.
    -Some think you can get away with the air box mod or removal of the exhaust baffle with the stock jetting, but not both.
    -block off the smog equipment.
    -a CRF450R cam.

    ?Do the JD kits come with smog equipment block off parts? I'm headed there (web site) next. How do you block off the smog equipment?

    Rode for 2 hrs. on monday for the first time. I like this bike so far.
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    Skoot22
    Posts:2380
    Joined:Sun Sep 03, 2006 9:51 pm

    by Skoot22 » Thu Mar 19, 2009 5:06 pm

    Airbox and Jetting is a must and needs to be done at the same time.

    You have an 08, you baffle is not removeable like the 05-07's

    JD kits come with 2 needles, a few main jets, and an o-ring for the ap mod, no smog block off stuff. Applied Racing makes a kit sold here. Or look in the stickies for smog block off done with JB Weld.

    05 450R cam is a great mod. At that point Jetting will need Richened up a touch, and Pink Wire mod
    Scott
    05 CRF450X
    Bakersfield, Ca
    Image
  • jsnotech
    Posts:90
    Joined:Mon Mar 16, 2009 12:45 pm

    by jsnotech » Fri Mar 27, 2009 4:15 pm

    Thanks
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    Kiwi
    Posts:363
    Joined:Thu Sep 25, 2008 12:22 pm

    by Kiwi » Fri Mar 27, 2009 5:18 pm

    Spanish Springs?! That's near my old stomping grounds (grew up in Carson City, went to college in Reno). I still ride with my buddies in Carson (we recently rode at Sand Mountain) and my 2007 450X has ... as runs great with:

    -Modified airbox including side slits cut out
    -Aftermarket air filter with factory backfire screen removed
    -stock idle/slow jet
    -172 main jet
    -NCYS needle on the fourth position (winter) and 3rd position (summer). Note: NCYS is a bit leaner than the NCVS. Done over I'd probably go for the NCVS.
    -CRFs Only idle screw
    -Pink wire mod
    -Factory exhaust header with Pro Circuit T-4 slip-on muffler
    -Aftermarket camshaft

    Thus, if your bike is all stock (factory exhaust, cam, etc) with the exception of the airbox mods and aftermarket air filter, I'd suggest:

    -stock idle/slow jet
    -165 or 167 main jet
    -CRFs Only idle screw (about 2 turns out)
    -NCVS needle on the third clip position

    If you later add aftermarket exhaust, up the main to a 170.
    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
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    belltownjefe
    Posts:47
    Joined:Sat Mar 07, 2009 8:22 am

    by belltownjefe » Fri Mar 27, 2009 5:25 pm

    Scoot has pretty much nailed it with the exception of the fuel screw. It is adjustable but a pain in the a$$ to do it. There are a couple of different methods to make it easier. Some guys shove a wire butt connector over it to turn it. They also make a wrench which isn't worth the $40 they want for it. The other option is rotating the carb and removing the float bowl to adjust it. Here is what I have done so far and I have the same bike as you. I ride the same elevation and climate.

    Year: 2008
    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
    Needle Clip Position: 4th
    Fuel Screw Type: Stock
    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


    I just got and adjustable Zipty Fuel screw that I should be installing here in a week or two. I need to dial my pilot a little bit, but so far the power and response is great from mid to top which kicks a$$ for open desert. I hope this helps.

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