Help XS250 DOHC Carb vacuum pipes

Discussion in 'Yamaha 250cc Twins' started by Xs250se, Aug 1, 2021.

  1. Xs250se

    Xs250se Active Member

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    Hello,

    Any one running a XS250 DOHC model 17A or 17E? trying to trace where the pipe fits on the carbs on a T junction between the carbs on the fuel feed? pic of parts diagram attached. The vacuum pipes on inlet rubbers and fuel supply are obvious fittings but this particular pipe is a myystery. it does not appear on the the DOHC xs400 models. the Japanese manual i have for the xs250 does not mention this pipe anywhere. My bike wont start after restoration so wondering if this is the cause. Is this pipe just a breather or is it part of the vacuum system?

    Many Thanks

    Richard


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  2. gregt

    gregt Well-Known Member Premium Member

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    It's a breather.
    Years back I had an XS250 in the shop - owned by a Priest. His complaint was that on the local motorway it would top out at around 100kph - then go progressively slower.
    After looking through the carbs and fuel system - and asking a guy who'd worked for the agents when they were new - I drilled out the fuel tap passages. Much improved performance.
    The local agent had done this as a warranty job when they were new. This one had slipped through the net.
     

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