2003 Crf450r cutting out under hard acceleration
  • 2003crf450r
    Posts: 13
    Joined: Sun Jun 07, 2020 5:09 pm

    2003 Crf450r cutting out under hard acceleration

    by 2003crf450r » Mon Jul 13, 2020 11:02 pm

    So I did a bunch of stuff to my bike full exhaust, quick shot 3, k&n with air box mod, big gun rev box just to name a few and now I’m getting this terrible stumble when I go to crack the throttle if I ease it all the way it’s much better but still almost unrideable it will randomly die and be hard to start back up I think it’s hot but I’m not sure I do have a boyesen supercooler, 1.8 rad cap, and some expensive oversized radiators (forget what they are not cheap eBay ones)so it’s hard to tell. I have been messing around with the fuel screw adjustable leak jet and pilot jet I switched the pilot from a 42 to 45 but it seemed to run worse so I switched it back and the main jet was a 185 which I thought was way too high I’m at sea level and temps are in the 70-90s right now I jumped down to a 180 but it seems no matter what I do it still won’t run right any help would be greatly appreciated.
  • Leardriver
    Posts: 416
    Joined: Wed May 05, 2010 10:33 am

    Re: 2003 Crf450r cutting out under hard acceleration

    by Leardriver » Wed Jul 15, 2020 5:59 pm

    When you do multiple things at once, its tough to say which one isn't working.

    First, a friendly admonition. Those bikes run fantastic bone stock. If you have the money to put all of those parts on it, buy a newer fuel injected version. They run even better.

    I suspect a plugged pilot jet passage, the area above where the pilot screws in, or a plugged accelerator pump reservoir in the bottom of the carb bowl.
  • 2003crf450r
    Posts: 13
    Joined: Sun Jun 07, 2020 5:09 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by 2003crf450r » Sat Jul 18, 2020 9:48 am

    Hey thanks for the reply, I didn’t plan on doing a bunch of stuff to it it’s just what I did during the whole stay at home for 3 months thing I needed to turn some wrenches to keep sane I have two kids under 2. It’s a supermoto now and I’ve barely gotten to ride it because of this issue. I changed the pilot to a 45 and then changed it back to a brand new 42 because it seemed to run worse, and I don’t think anything is clogging the accelerator as I can see fuel squirting into the carb. I did put a boyesen quick shot 3 on it and it’s when the problems started. I had the diaphragm on upside down and wasn’t getting any fuel squirt so I figured it out and flipped it back over and now I’m getting fuel squirt but when I crack the throttle it hesitated and sputters real bad then goes but runs shitty. It will stall and be hard to start the idle does sound a little funny but I did just swap the exhaust out so maybe it just sounds different than I’m used to. I bought the bike in North Conway nh in the winter and it’s cold and there’s mountains there I live at sea level and it’s 80s right now. the jd jet kit that came with it in the instructions it said to use a 185 main and I think last position on the needle I was thinking that was too much on the main so I changed it to a 180 but of course the jet broke inside the imulsion tube so I had to take it out and get the half of the jet out. It seems like it could be the accelerator pump but I don’t know where to start or what to do it’s getting a nice squirt last I saw when I had the rear subframe off to replace the back shock. I have played with both the fuel screw and adjustable leak jet but it seems to stay the same. I want to just drop it off at a dealership but i think they’ll be swamped and or rip me off. I was thinking about just buying a lectron carb but idk if I want to spend that money I’ve already done so much to it I just want it to run right. One other stupid thing I did was when I took the float bowl off to put the quick shot on I took the fuel screw out and didn’t know there was supposed to be a washer and o ring on the fuel screw but I have since fixed that I’ve looked at how it is supposed to go on and in some pictures it’s the o ring and washer first then the spring in others it’s the spring first currently I have it spring washer o ring if that’s right. Any other suggestions or help would be greatly appreciated if any one is in my area and can help me out I will pay them. I live in north shore mass.
  • 2003crf450r
    Posts: 13
    Joined: Sun Jun 07, 2020 5:09 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by 2003crf450r » Sat Jul 18, 2020 9:49 am

    Hey thanks for the reply, I didn’t plan on doing a bunch of stuff to it it’s just what I did during the whole stay at home for 3 months thing I needed to turn some wrenches to keep sane I have two kids under 2. It’s a supermoto now and I’ve barely gotten to ride it because of this issue. I changed the pilot to a 45 and then changed it back to a brand new 42 because it seemed to run worse, and I don’t think anything is clogging the accelerator as I can see fuel squirting into the carb. I did put a boyesen quick shot 3 on it and it’s when the problems started. I had the diaphragm on upside down and wasn’t getting any fuel squirt so I figured it out and flipped it back over and now I’m getting fuel squirt but when I crack the throttle it hesitated and sputters real bad then goes but runs shitty. It will stall and be hard to start the idle does sound a little funny but I did just swap the exhaust out so maybe it just sounds different than I’m used to. I bought the bike in North Conway nh in the winter and it’s cold and there’s mountains there I live at sea level and it’s 80s right now. the jd jet kit that came with it in the instructions it said to use a 185 main and I think last position on the needle I was thinking that was too much on the main so I changed it to a 180 but of course the jet broke inside the imulsion tube so I had to take it out and get the half of the jet out. It seems like it could be the accelerator pump but I don’t know where to start or what to do it’s getting a nice squirt last I saw when I had the rear subframe off to replace the back shock. I have played with both the fuel screw and adjustable leak jet but it seems to stay the same. I want to just drop it off at a dealership but i think they’ll be swamped and or rip me off. I was thinking about just buying a lectron carb but idk if I want to spend that money I’ve already done so much to it I just want it to run right. One other stupid thing I did was when I took the float bowl off to put the quick shot on I took the fuel screw out and didn’t know there was supposed to be a washer and o ring on the fuel screw but I have since fixed that I’ve looked at how it is supposed to go on and in some pictures it’s the o ring and washer first then the spring in others it’s the spring first currently I have it spring washer o ring if that’s right. Any other suggestions or help would be greatly appreciated if any one is in my area and can help me out I will pay them. I live in north shore mass.
  • Aussiecrf230
    Posts: 1724
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by Aussiecrf230 » Sat Jul 18, 2020 2:33 pm

    So let me get this right, on the fuel screw you put the spring over first, then the washer and then the oring?

    Is that correct?

    Have you checked what Leardriver has suggested, if not the do it whilst fuel screw is out and clean its passageway as well.
    Ray
    Australia

    CRF230F 2004
    C30F Power Up needle
    Mains 132
    Idle 45
    2 turns out
    Baffle out, Screens In

    It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas
  • User avatar
    JimDirt
    Posts: 3789
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by JimDirt » Sat Jul 18, 2020 3:39 pm

    If the issues STARTED when you installed the QS3 , that is where I would look ..... you need to adjust it according to the instructions , that is the leak jet screw on the side , and if it is not correct , you will have issues ..... A buddy of mine put one on his 2011 KTM 450SXF , and he ended up killing the battery trying to start it , and keep it running .... I looked at the instructions , checked the setting , and it was way off , I adjusted it to what the instructions said and the bike fired right up , it was still temperamental , but better .... personally I prefer the QS2 , it does not have the adjustable Leak Jet , and it works so much better ....

    The main purpose of the QS pump covers is to give you more gas volume in the AP , the Leak Jet add on , to me is too much for minimal benefit and more adjusting needed to be done ... basically its Snake Oil for your carb , you are better off just buying the correct size leak jet and forget the adjustable one , there is really no need for it , all it does is regulate the BY-Pass fuel that the AP does not use in the squirt ... but it makes tuning a nightmare as far as I am concerned ................... [-(
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho
  • 2003crf450r
    Posts: 13
    Joined: Sun Jun 07, 2020 5:09 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by 2003crf450r » Tue Jul 21, 2020 5:42 pm

    Yes I put the spring on first then the washer then the o-ring and the leak jet that was in my carb said 55 so the directions said to turn 1 1/4 turns out for 55 I keep playing with it and the fuel screw but I think something else is wrong. I put on a big gun rev box at the same time and a power x wing could it be the rev box? Or the needle clip position? Or maybe too big of a main jet?
  • User avatar
    JimDirt
    Posts: 3789
    Joined: Sat Nov 25, 2006 6:31 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by JimDirt » Tue Jul 21, 2020 7:12 pm

    Go by this Jetting Guide , it does not matter what everyone else says to do , these setting should make the bike run the way it should ... jetting is dependent on Elevation , and Temperature .... the exhaust should have some but slight differences , because of flow , but regardless , go by this table and report back ... unless you have something electrical going on , this should work ....

    And what is your elevation ??

    Jetting Guide for Main Jet:(pilot 45) CRF450R/X

    Sea level....165
    2000 ft.......162
    4000 ft.......160
    6000 ft.......158
    8000 ft.......155


    Temperature/Elevation:
    One main jet size (up/down) for every 2,000 feet or 25 degrees in temp.
    02 CRF450R
    06 CRF450X
    Image
    Weiser , Idaho
  • 2003crf450r
    Posts: 13
    Joined: Sun Jun 07, 2020 5:09 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by 2003crf450r » Sat Aug 01, 2020 3:03 pm

    I finally figured it out... my bike was down and I couldn’t work on it while I was waiting for my bar clamps. I bought a scar triple tree and the seller failed to mention it required special bar clamps that were of course no where to be found I got the last set of them in the world from Australia scar is out of stock for a month at least they said but anyway that’s what was taking so long. So I finally decided to take a peek at the needle because I had gone through and changed everything else and it was at the last position on the bottom I changed it up three and bang the bike is running mint. I have a 42 pilot 2.5 screws out of the fuel screw which might mean I should switch to a 48 but it’s running perfect so I might not touch it and a 180 main red needle on the 5th position. So it was the needle it seemed like it was the accelerator pump because if I gave it more than half throttle it would stumble and die I checked the plug and it was slightly black on the very bottom the rest looked wet and smelled like gas
  • Aussiecrf230
    Posts: 1724
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by Aussiecrf230 » Sat Aug 01, 2020 5:09 pm

    If you are 2.5 turns out a 45 idle jet should fix that.
    Definitely start dropping size of main jet to clean up top end too.
    Ray
    Australia

    CRF230F 2004
    C30F Power Up needle
    Mains 132
    Idle 45
    2 turns out
    Baffle out, Screens In

    It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas
  • 2003crf450r
    Posts: 13
    Joined: Sun Jun 07, 2020 5:09 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by 2003crf450r » Wed Aug 05, 2020 7:39 pm

    I did change it to a 45 pilot and the fuel screw wouldn’t make a difference all the way in or out so I switched back to 42. What I don’t get is how it was running fine almost stock then I do the air box mod change it out to a K&n air filter add a big gun rev box a quick shot 3 a boyesen power wing a power bomb header and bbr silencer and a couple other mods that would affect jetting and instead of needing to go richer I needed to go leaner it’s weird. The bike had a 185 main and red needle on the second to last clip and ran fine occasionally stumbling but not like it was. I went to change the main jet and wen I tried to take the 185 out it snapped inside the carb so I had to take the Imulsion tube out and get it out and put a 180 main in and it was like screwing in a messed up screw the whole way I was afraid to tighten it so I bought a carb rebuild kit that came wi th w new imulsion tibe I’m going to put it and go a little lower on the main see if that does anything but it seems to be running great right now.
  • Aussiecrf230
    Posts: 1724
    Joined: Fri Jan 06, 2006 11:11 pm

    Re: 2003 Crf450r cutting out under hard acceleration

    by Aussiecrf230 » Wed Aug 05, 2020 8:07 pm

    The thing with an idle jet is you only need so much fuel to keep it running.
    It rarely needs much more fuel and if you improve the pumping efficiency of the engine with exhausts etc that all work together you sometimes need less fuel as the incoming charge into the engine is less polluted by the previous cycle of exhaust gas.
    Ray
    Australia

    CRF230F 2004
    C30F Power Up needle
    Mains 132
    Idle 45
    2 turns out
    Baffle out, Screens In

    It starts,it runs,it gets to where all CRFs can get to without the valve or valve plate dramas

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