08 250r jetting question
  • honda fan
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    08 250r jetting question

    by honda fan » Thu Jul 28, 2011 9:40 am

    I have an 08 crf250r with twin air filter and cage. Full yoshimura exst and a r and d power bowl. Im runin a 190 main and a 50 slow jet. After reading some posts on here I seem way to rich but the bike rips rite off idle and all the way threw. But wen it gets warm it will only start with the hot start and if it stalls it can be a bear. I jst dnt no if I wana mess with the jetting to get it startn bettr and risk messin up the way it runs now. Should I go leaner
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    crfsonly
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    by crfsonly » Thu Jul 28, 2011 10:57 am

    starting, idle and off idle is the domain of the pilot circuit. so, it's pretty easy to swap pilot jets. hot bikes like a leaner mixture to start. this is what the hot start does..introduces more air to the mixture. so, you could experiment with going down on the pilot jet as well adjusting your fuel screw. just keep good notes on the jet and fuel screw changes and you can also go back to the best set up.

    ken
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    by honda fan » Thu Jul 28, 2011 11:04 am

    Ill give that a try cause jst like u said I can always come back to were im at now. Thanks for the help
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    crfsonly
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    by crfsonly » Thu Jul 28, 2011 11:10 am

    here's a how-to on swapping jets/needles if you need it:

    http://crfsonly.com/howto/450x/jetting/ ... needle.php
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    by honda fan » Fri Aug 12, 2011 1:35 pm

    Jst put a jdjet kit in my bike with the red needle with a 185 main and took the pilot dwn from a 50 to a 42 . Its got a lil bog off bottom wen I throttle hard. It starts alot betr but will only start with the hot start.
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    by Mark Mitchell 32 » Fri Aug 12, 2011 3:12 pm

    My 450 loves the hotstart. I mean, even when its cold, I have to use the hotstart. I have to change my jetting too.
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    crfsonly
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    by crfsonly » Fri Aug 12, 2011 3:18 pm

    in both cases have you adjusted your fuel screw? you should not need the hot start when the bike is cold. if you do then your pilot circuit is too rich. fuel screw can help if you have the correct pilot jet. if the pilot jet is too large then you'll need to go down one and adjust the fuel screw from there.
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  • Mark Mitchell 32
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    by Mark Mitchell 32 » Fri Aug 12, 2011 3:26 pm

    In my case, I just have to get the screw dialed in. The jetting is JD's recommended setup.
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    by honda fan » Fri Aug 12, 2011 3:27 pm

    Yea I tryd the fuel screw sum help nothin too major. I've had a 40 ,42 , and 45 pilot in it today it was pretty good with the 42 . The 40 it got worse to start. With the 45 the bog off bottom got bad.
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    by honda fan » Fri Aug 12, 2011 3:31 pm

    Im goin back to the 42 pilot now and im gona try playin with the fuel screw lil more. It seemed to start betr with that jet it jst had a lil bog if u gased it from off idle to bout 3/4 throttle.
  • Keith72
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    by Keith72 » Sun Aug 28, 2011 8:15 am

    You should be using a 172-175 main jet. That large main you are running is probably responsible for the bog when you open the throttle quick. When you snap the throttle to wide open quick it starts pulling from the main jet right away and your 185 main is too big. Most guys with your set up are using a 42 pilot and a 172 main. Honda jetted these bike super rich from the factory.
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    by honda fan » Sun Aug 28, 2011 8:33 am

    I got a 180 main in it now and it seems to me like it mite b lil to lean . It dnt have any bog in it. Now wen I get it opened up it starts to get real choppy like its wantin to cut out.
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    by Keith72 » Sun Aug 28, 2011 8:48 am

    Did it start acting this way when the weather got hot? Was it this way in the spring when the weather was a lot cooler? If your answer to the first question is yes and the answer to the second is no, you are too rich on your main jet.
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    by honda fan » Sun Aug 28, 2011 8:57 am

    No all the jetting I've been doin has been in thelast few weeks. Its been sunny and warm.

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