Exhaust/vacuum leak

Discussion in 'Mechanics Garage' started by akaspeedfreak, May 18, 2017.

  1. akaspeedfreak

    akaspeedfreak New Member

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    So I am the only owner of 26k mile 2004 vfr800. Recently i was riding and while at a stop noticed not only did the idle seem rough but the sound of sonething like a disconnected intake vacuum line. So straight home and on center stand used a camera snake to find the rear right or #3 cylinder was the source of my sound and performance decline. At the base of the head approx 2in below the exhaust manifold is a small 3/16 inch hole. The hole was inhaling and exhaling with each stroke of the motor. What is the purpose of this hole and how do I go about fixing?

    I have already spoke with my long time honda mechanic that does all my machine work and he is perplexed by this. No oil in radiator or coolant in oil. Possible head gasket?

    Please help
     
  2. RllwJoe

    RllwJoe Insider

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    First of all, a big welcome to VFRWorld!

    When I saw your post, I immediately grabbed my service manual to see if a vacuum line is located in that area.
    I have a 5th gen, so we may be missing something that is different from mine.
    However, the head gasket is the only thing that I can see that is below the exhaust outlet.
    It would be great if you had a vacuum line disconnected, but again, I don't think it has any vacuum connections on the exhaust side of the cylinders.
     
  3. akaspeedfreak

    akaspeedfreak New Member

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    It is a machined port and yes i have seen it on the 5th gens. Infact while at the shop I pointed it out on a 5g. When he called Honda they told him(my Honda mechanic) that was just part of thr manufacturing and exhaust couldnt come out if it. Really hate ti pull it all apart if thats not it.
     
  4. TOE CUTTER

    TOE CUTTER Mullet Man

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    On the earlier gens the spark plug recess had a hole at the base that vented oot the side of the head to drain fluids that could find their way down around the spark plug, like an oil leak from a valve cover. I have not rummaged aboot in the later gen engines like I have the older ones but I would guess that is what it is as the heads are configured with the drive on the side in the later gens. That being said, if I am correct I would also guess it may be a loose spark plug causing your issue.

    pic of drain hole on older gen bike......not a great pic.

    https://www.google.com/search?q=vfr...r+750+cylinder+head++++&imgrc=5ovkPe9cDQLh6M:
     
  5. akaspeedfreak

    akaspeedfreak New Member

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  6. RVFR

    RVFR Member

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    Definitely a 6th gen bug a boo for sure, my 5th gen doesn't have them. I'm incline to say they're there for machine handling at the factory. My first guess is, if you have exhaust coming out of that your into something very serious I'm afraid to say.
     
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