Heavily Modded 2004 CRF450R Jetting Question
  • nikoN^
    Posts: 2
    Joined: Tue Dec 06, 2016 8:00 am

    Heavily Modded 2004 CRF450R Jetting Question

    by nikoN^ » Tue Dec 06, 2016 8:20 am

    Hello everyone, this is my first post on CRF's only and I need y'all's help. I am going to to be going to New Mexico for a three day ride at the end of this month, and the altitude of Rio Rancho, is around 5,200 ft, while where I normally ride in Arizona is around 1,200. So naturally I really need to change my jets.

    Bike: 2004 CRF450R

    Here's a list of mod's done to my bike's powerplant:
    Athena 500cc big bore kit
    Wiseco 101mm (5.0+) 12.5:1 piston
    Kibblewhite stainless steel valves
    WebCam Mysto camshaft
    Ported head and ported carb
    Oversized intake and exhaust valves (+1 or 2 iirc)
    Stainless steel header tuned by Dynojet (Stage 3)
    FMF Titanium muffler
    Hinson Full Clutch kit (I can't remember if it was the Billetproof or Momentum)
    Trail Tech flywheel
    Vortex Programmable CDI box
    JD jetting kit
    NGK IFR9 Spark plug
    Uni are filter
    12T Front, 48T Rear 520 chain
    I run a 21in front wheel and 19in rear

    For oil I run Bel Ray's EXP Synthetic Ester at 10w40.

    What do you guys recommend that I use for taking this bike to NM? It will be the highest altitude the bike has ever seen. Thank you guys for all the help.
  • Leardriver
    Posts: 462
    Joined: Wed May 05, 2010 10:33 am

    by Leardriver » Tue Dec 06, 2016 11:41 am

    In winter temps, a 158 main. Leave everything else alone. The main is only for wide open throttle or close to it anyway. in summer, a 155.

    Big bores usually require a leaner main. I know that sounds backwards. An engine is an air pump, and a more efficient air pump with higher compression, porting, more cc's pulls more fuel through any given jet.
  • nikoN^
    Posts: 2
    Joined: Tue Dec 06, 2016 8:00 am

    by nikoN^ » Tue Dec 06, 2016 1:07 pm

    In winter temps, a 158 main. Leave everything else alone. The main is only for wide open throttle or close to it anyway. in summer, a 155.

    Big bores usually require a leaner main. I know that sounds backwards. An engine is an air pump, and a more efficient air pump with higher compression, porting, more cc's pulls more fuel through any given jet.
    So I should leave everything else alone even though it's dialed in for 1500 feet? I presume that would mean just changing the main and then fine tuning with my air fuel mixture?
  • Leardriver
    Posts: 462
    Joined: Wed May 05, 2010 10:33 am

    by Leardriver » Tue Dec 06, 2016 4:36 pm

    Yes, that is a perfectly good starting point, and you may not have to touch it.
    These bikes run pretty well when the jetting is way off, and you will be way close.

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