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Carb bowl fuel leakage

in 912 / 914 Technical Questions 7 years ago
Carbs just rebuilt from Lockwood and when installed engine ran rough above 27MP. Checked everything and found fuel staining on the bowl to carb. Pulled off and checked the bowl is flat and gasket looks good. Reassembled got past the roughness but still seeing fuel staining on the bowl and drain shield after full power run up. Has anyone had better luck with the cork or nitril gaskets available on eBay? Looks like the BMW motorcycle folk use them. I need to get this to seal! Ideas or suggestion?

  • Re: Carb bowl fuel leakage

    by » 7 years ago

    Which model of engine do you have??
      
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  • Re: Carb bowl fuel leakage

    by » 7 years ago

    914
      
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  • Re: Carb bowl fuel leakage

    by » 7 years ago

    Sometimes if the 914 float bowl fastening nut is over-torqued, the bowl can become distorted. (Not usually a problem on 912, since it uses a clip rather than a nut). Sometimes a cork gasket can workaround this, if the distortion is minor. Have you replaced the O-ring on the fastening nut? Have you checked out our video about rough running, or our other related carb videos?
      
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  • Re: Carb bowl fuel leakage

    by » 7 years ago

    Thanks, yes I have checked the videos. I did pull the float bowl and tried to give it a fine polish with some wet sanding on a flat glass plate with some very fine emory paper to see that the surface finish was smooth and flat. I have not changed the nut o-ring but assume it is new from being rebuilt. The oring looks to be in good shape. Torque is right at 48. I ordered a set of cork and the rubber seals to see if they seal. While waiting on them to arrive I plan to try to isolate the carb from the prop wash to see if I can locate the source of the leak. Sitting with the pumps running shows no trace. Running up to full power is when I seem to get the seeping. It's not enough to cause a rough running engine but fuel needs to stay inside the system!
      
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  • Re: Carb bowl fuel leakage

    by » 7 years ago

    Leakage is not coming from the float bowl. Installed a cork gasketbut no change. Got someone with a camera to film the leak. Still can't see for sure where it's coming from but appears to be above the float bowl and looks to be near the throttle shaft.
      
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