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Running lean then running rich

  • Chaz Newby

    So I’m just trying to understand exactly what i could possibly be doing wrong. I have a 2005 Honda Shadow 600. it has the boot burner exhaust, velocity stack and i just installed the max performance/tuning kit on the carburetor, im getting a rough idle and black smoke out of the exhaust even with the mixture screw all the way closed. I used the smallest main jet and pilot jet supplied with the kit. Would it help if i used only one needle shim and if i didn’t put the TPS back in the exact orientation would that cause an issue with anything? I’m just trying to find some straight forward answers if possible
  • TJ

    @Chaz Newby

    Black smoke could mean you're running stupid rich. Since you're getting that at idle even with the mixture screw all the way in, I wouldn't start changing the needle shims yet. The needle and main jet have very little effect at closed-throttle idle.

    First, I'd go back through the carb and verify a few things: make sure the choke/enricher plungers are fully seated, they can get corrosion in them. then make sure the float and float needle are operating correctly and the fuel level isn't too high, verify you have the correct pilot jet installed, and double-check the mixture screw assembly including the spring, washer and O-ring.

    I would also put the TPS back as close as possible to its original orientation. TPS position can absolutely affect ignition/throttle-position information, although I wouldn't expect that by itself to cause black smoke and an extremely rich idle.

    Before changing any more jetting, I'd want to figure out why it's getting so much fuel at idle. Also, did the bike idle and run normally before the carb was opened up for the kit installation?

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