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Leaks gas when the bike is warmed up?

Discussion in 'The Garage' started by Savon Gaiter, Apr 1, 2018.

  1. Savon Gaiter

    Savon Gaiter XS650 New Member

    I have an 83 Yamaha xs650 ive bought mikesxs carbs (assembled) , mikesxs non vacum petcock and for some reason its still leaking gas. The leak only happens when ive rode the bike awhile it comes from the left carb from the overflow vent hose. I had someone tell me it could be the ignition or timing something like that
  2. bluesman650

    bluesman650 XS650 Enthusiast

    The ignition or timing would have nothing to do with fuel leaking. I would suspect improper float level or sticking float valve.
  3. Savon Gaiter

    Savon Gaiter XS650 New Member

    But its only when the bikes been running for awhile. The carbs are brand new
  4. 5twins

    5twins XS650 Guru Top Contributor

    Unfortunately, Mikes sells some carbs of questionable quality, in particular the PWKs. Sounds like that may be the ones you got. They have been not so affectionately nicknamed the "Pukes" because, well, many times that's just what they do, lol. It doesn't matter that they're new. The problem is poor quality control during their manufacture. Parts don't fit right, stick, hang up, etc. Sounds like when yours heat up and parts expand, something's sticking.
    grizld1 likes this.
  5. Savon Gaiter

    Savon Gaiter XS650 New Member

    So like bluesman was saying it could be the float value sticking ? Ima take them apart for now and look at the floats and etc.
  6. electra_boogaloo

    electra_boogaloo XS650 Enthusiast

    i have the same problem but mine leaks when it's sitting still. i'm still trying to get it started and running right atm. let us know when you fix it

    edit: sidenote: i inherited the mike's xs kit. i think they look neat, but if they don't run they don't run, what is the general agreed upon replacement carb for these bikes?
  7. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    grizld1 and electra_boogaloo like this.
  8. grizld1

    grizld1 Grumpy old man Top Contributor

    Guys, the best you can do with those PWK knockoffs is still very bad. Even if you spend time and money correcting defects, you're still stuck with needle jets (AKA "atomizers," AKA "emulsion tubes") that are too rich for 4-stroke applications, and no alternative sizes are avaailable. Return the carbs if you can, use them for paperweights (and desktop reminders to do your research before the sale, not after), and buy a pair of real carburetors. Gary's suggestion is a good one if you're lucky or know what you're doing, but when you buy used carbies there's always a possibility that Og the Cavewrench has been into them. For new gear, the least expensive and least troublesome carbs you can buy are Mikuni VM34s. There's plenty of information on these, so you can do some reading and find out what to expect (if you buy from a cheap source, what you can expect is grief and expense).
    gggGary likes this.
  9. I’m not familiar with the mikes carbs but I had a Niki I carb on a sportster so that last year, it could sit for weeks and not leak a drop, go out and ride it for a bit and it would just pour gas out the overflow. I found what looked like some insects nest in the vent for the float bowl, blew that out with carb cleaner and compressed air and it never happened again. With these being new carbs I’d say 5T is probably right though. But it’s worth checking, good luck

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