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Carb fuel flow

Discussion in 'The Garage' started by Robert Dell Aquila, Jan 11, 2019.

  1. Hi yall, trying to figure out my idle issue with my 78'XS650-E 277 rephased. Running pamco 277 ignition with 3 ohm single output coils. Intitially my bike would idle fine then die after about 10 minutes and not start back up. Now it does not idle at all after I cleaned the carbs. Since I'm getting spark and have compression. I assumed the carbs were at fault. I have bs38 carbs with stock jetting 135 main 27.5 pilot I believe. Set the float height to 24mm(+\- 1mm). I believe that not enought fuel is getting into the carbs. I took out the float bowl drain screw and turned the petcock on and no fuel flows through the system. However, it flows out of the petcock without the fuel line attached. I read somewhere that the paper filters I have, do not flow well if there is not enough fuel in the tank. Just wondering what fuel lines and filters you guys are running and how it hooks up. Below is a picture of my setup. Any help is appreciated thanks!

    Attached Files:

  2. 5twins

    5twins XS650 Guru Top Contributor

    In it's stock configuration, the fuel outlet on your petcock should be facing the rear. The way you've got it with that long hose on the outside, you're trying to push fuel uphill, and that, combined with a restrictive filter, may be the problem. Personally, I don't run any extra filters. I just rely on the screens in the petcock and carb to filter stuff. So far, I haven't had too many problems. I think I had to clean my carbs once in the past nearly a dozen years, and the bad running issue may not have even been carb related. I found a loose battery cable as well and that could have been the cause.


    I'd switch the petcock around and run a shorter, only down hill fuel line with no added filter.
    Last edited: Jan 12, 2019
    TwoManyXS1Bs likes this.
  3. Hey thanks for the quick response. Will give it a go and see if I get better fuel flow. Appreciate it.

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