Fuel tap different? 3 ports, vacuum issue
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Thread: Fuel tap different? 3 ports, vacuum issue

  1. #1
    Junior Biker
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    Fuel tap different? 3 ports, vacuum issue

    Have an issue with my MC22 in that it's suddenly pissing a hell of a lot of fuel over the engine and its coming from this 'extra' port that I can't find mention of by anyone



    I have pulled it apart as much as I can, can't really get into it at all the only access I have is to the vacuum diaphragm. No obvious damage there. The way it appears to work is that middle port actually gets exposed when vacuum is applied to the outer port. Since fuel didn't actually flow much from there in the past my best guess is it was clogged with debris, and it has worked its way loose now allowing fuel to flow from there as well.
    Is this a genuine CBR250RR fuel tap or has some dickery gone on here?

    Since the fuel tap doesn't actually leak i'm thinking of just blocking that port off, can't see how it would cause any harm unless there's something i'm missing entirely

  2. #2
    Biker phreak911's Avatar
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    The third port is actually a breather for the back of the vacuum diaphragm (the smaller hose that comes from your motor), if you block it the diaphragm wont be able to open, which will stop fuel flowing through the tap. You need to take the tap off the fuel tank, open it up (drill out the rivets), and replace the rubber o-rings and give the whole assembly a good clean out. Be careful, there is a little spring and ball bearing inside the rotating assembly that will pop out and fly to another dimension if you're not careful. Take pictures, post them up if you have any other questions. You can make a new gasket for the bigger side out of good quality gasket paper, as the proper gasket is almost impossible to find from a supplier. When its all finished, replace the rivets with bolts and lock nuts, so you can take it apart easily if you need to do it again later down the track. Oh, and do NOT be tempted to stretch the spring behind the ball bearing, it only needs a tiny amount of pressure to seal the inlet flow holes inside the tap. Good hunting!
    Last edited by phreak911; 30th May 2017 at 01:42 AM.
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