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Only firing on one cylinder.

Discussion in 'The Garage' started by BCoop, Jul 17, 2018.

  1. BCoop

    BCoop XS650 Addict

    My 1975 XS with bs38 carbs was idling and running great a day ago. The only problem is that the carbs were dumping fuel out of the over flow!

    I bent the tabs on the floats so that they would stop pouring gas everywhere lol. This stopped the gas from coming out of the over flow but the right cylinder stopped firing. So I split the difference on the float height and it still isn't firing.

    Do float heights have the ability to keep a cylinder from firing? The right cylinder just has a hiss through the carb.
  2. xjwmx

    xjwmx XS650 Guru Top Contributor

    To start with set the floats to the spec. height. Float height needs to be within 1mm or so of spec to run right. Might not fix your problem, but you have to start with carbs set up right.
  3. BCoop

    BCoop XS650 Addict

    Will do! Thank you!
  4. cmarts

    cmarts XS650 Enthusiast

    I had the same issue with my bike when I first got it. Turned out the one carb on the side that wasnt firing required alot more cleaning. Took it apart again and went through it with a small wire, lots of carb cleaner, and an air compressor.
  5. perki48

    perki48 XS650 Enthusiast

    I purchased XSPerformance carbs from MikesXS and right cylinder was not firing at idle. Turned out to be Idle adjustment needed to be turned in much further on that side to work properly.
    cmarts likes this.
  6. BCoop

    BCoop XS650 Addict

    Thanks for all the advice! I set the floats to 24mm from the gasket seat to the top of the floats. I then made sure they were level. I cleaned the carbs and put them back on but the left carb is still over flowing. I put both floats in a container full of water with a lid to keep them submerged over the weekend. Hopefully by Monday when I get back to the shop they will still be floating.

    I've always liked the way that the single carb looks and have been knocking that idea around a bit lately. Does anyone have any experience with how a bs38 would run by itself feeding two cylinders? I live close to the wheels through time museum and a lot of the old racing bikes on display have a single side mounted carb which is where I first got the idea from.

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