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Problem with fueling.

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  • Problem with fueling.

    Hi everyone,

    Ive got a problem with my 99 750 Katana that I need some input on. A week ago I noticed that she was running a bit rough so I decided to take the carbs off and clean. Ive cleaned the carbs on this bike a half dozen times and was very careful to make sure everything went back in place. No worries there. So I get everything back in order and start her up. I can immediately tell that all four cylinders aren't firing and sure enough after check the headers the far left cylinder is the culprit.

    I took the carbs back off and checked. Each is getting fuel. So I lift the slides and butterflies and see that there is fuel pooled around the valve on the cylinder that's not firing. This doesn't seem good at all. What do you guys think?

    P.S. - I just had the valves adjusted about 3000 miles ago.

  • #2
    Bad plug/wire. Bad float needle
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    • #3
      Originally posted by 92xjunker View Post
      Bad plug/wire. Bad float needle
      Thanks for such a quick response! Wouldn't the accumulation of fuel be in the exhaust port if the plug was bad? (fuel not combusting then forced out through exhaust valve during exhaust stroke). The fuel is just sitting on top of the intake valve....


      • #4
        Simple test..

        Use prime, and fill the carbs.

        Turn prime off.

        Carefully remove the fuel line, careful to not spill any fuel out of the fuel line.

        Wipe off the end of the fuel line.

        Now blow hard on it. Does the fuel go down, any air move at all. Hear bubbling? Any of that tells you that a float needle is an issue. Open up the carbs and check again. Generally you can narrow down which is the problem.

        You can use water with the carbs off the bike to do this test, so after you adjust and check them, fill with water, test... open and check again, test... so on until you know it's not letting liquid past. Just make sure you remove the carb bowls and dry out the carbs if you use water, before putting them back on. That shouldn't have an affect on the final setting for the float needles though.

        I'd also check your plug wires/plug caps. Make sure no arc when running (run in low light with the tank off it's easy to see), and you may need to clip back the last 1" or so of plug wires, as they harden and loose connectivity.

        93 750 Kat

        Modified Swingarm, 5.5 GSXR Rear with 180/55 and 520 Chain, 750 to 600 Tail conversion, more to come. Long Term Project build thread

        "I've done this a thousand times before. What could possibly go wron.... Ooops!"