ASK THE MXPERTS: 2007 HONDA CR250 BOG

June 18, 2010
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Dear MXA,
    Just wondered if you could hook me up with the best jetting specs for a 2007 CR250? I hate the way my CR250 two-stroke runs.

    The jetting on the 2007 Honda CR250 was a mystery to everyone who owned one. It’s not that we couldn’t get the jetting to be spot on, it’s just that we couldn’t keep it there for more than three hours. Everyday was an adventure in brass. We eventually learned to accept that the CR250’s lean jetting would be tomorrow’s rich jetting. Here is the 2007 Honda CR250 jetting we ran:
    Main Jet: 420
    Pilot Jet: 38 (40 stock)
    Needle: 6DGY-26-65
    Clip: 2nd from top (3rd stock)
    Air screw: 2 turns out
    Note: 2007 Honda CR250 jetting is a conundrum. It’s rich on the bottom, but lean everywhere else. When you lean out the bottom, the CR’s pinging gets more ominous. Honda’s engineers claim that the pinging isn’t a jetting problem, but some sort of mechanical sound (and suggested that we ignore it). It’s hard to accept that explanation because jetting changes make it louder. On a daily basis, our best solution was a dose of race gas (mixed with pump gas), a leaner pilot and lots of fiddling with the clip position
.

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