Where to start when re-jetting a lean 450x?
  • Candelz
    Posts: 1
    Joined: Wed Mar 02, 2016 7:18 pm

    Where to start when re-jetting a lean 450x?

    by Candelz » Wed Mar 02, 2016 8:01 pm

    Hello,
    I recently purchased a 2006 450x, and I'm hoping someone can give me some advice on rejetting. The previous owner installed a DRD full stainless exhaust, and did the airbox mod. He bought a JD's Jetting kit and said he followed the instructions when he rejetted it. I don't know what jets are in it, but I know the stock pilot, main, and needle are all in the kit and not in the carb. I also know that the bike is still running lean. At night the header will glow a slightly reddish purple after it's been warming up for a minute, and the most noticeable symptom is the popping under engine braking, it gets pretty severe under hard decel and is alleviated some by cracking the throttle a hair while braking. So my question is where should I start? Should I adjust all the jets and the needle one step richer and see where that gets me? Or one jet at a time? If so which one? Any insight would be greatly appreciated.
    Thanks,
    Matt
  • Leardriver
    Posts: 462
    Joined: Wed May 05, 2010 10:33 am

    by Leardriver » Thu Mar 03, 2016 11:35 am

    A perfectly jetted and tuned 450 will pop a bunch on decal, and have the head pipe glow red when it doesn't have a lot of airflow, as in sitting and idling.

    A 45 pilot and 165 main should be exactly right for under 2,000 feet elevation.
    Those bikes will run pretty good with the main jet several sizes big or small. Unless you measure air/fuel on a dyno, it is hard to know.

    Jetting is never perfect. If you start riding at 60 degrees in the am, and quit when it is 85 in the afternoon, you are already 1 size off. It is a continually moving target as your ride changes elevation and temperature.

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