Strange clutch related noise

Discussion in '5th Generation 1998-2001' started by DaHose, Dec 6, 2017.

  1. DaHose

    DaHose Active Member

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    Hey folks. I got the vacuum hoses all replaced and the wax unit issue fixed, but now something really weird is going on.

    If I start the bike and let it idle everything is fine. When I put it into gear with the clutch still in, everything is fine. The second I engage the clutch at all, there is a high pitched, pulsing noise. Nothing seems wrong at all, other than that noise. At first I thought it could be the bodywork squeaking under vibration, but I can't track it down to any single panel, and it kicks in the instant I start letting the clutch lever out. Anyone run into this, or is it just me?

    Jose
     
  2. OZ VFR

    OZ VFR Active Member

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    Flapper hose connected?
     
  3. DaHose

    DaHose Active Member

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    I am positive I re-connected that hose before closing everything up, but I'll check again.

    Jose
     
  4. DaHose

    DaHose Active Member

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    You were on the money, Oz. There is a vacuum check valve feeding the flapper solenoid and the vacuum reservoir. I plumbed it in wrong, so the flapper was starving for vacuum. As a result, releasing the clutch in gear would trigger the flapper solenoid, and the lack of vacuum would cause the flapper to flutter. The original location for the check valve was under the airbox, right next to the flapper solenoid. That made removing the airbox a pain in the ass, and left the plastic check valve in the hottest part of the engine V. On re-assembly, I moved the check valve so I can easily reach, and disconnect it to remove the airbox. Problem solved.

    Jose
     
  5. OZ VFR

    OZ VFR Active Member

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    That air box/throttle bodies are a pain in the arse to remove/reinstall.
    But once you've done it once, it gets easier.
    Glad you sorted it.
     
  6. DaHose

    DaHose Active Member

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    Yeah, now that I have removed them, I hope I won't need to do that again during my ownership. I had to buy one tool for it too. A 12" long phillips head bit for my little cordless screwdriver. You really have to fish around under there to get at the clamps holding it on. Thank the stars for youtube. I am convinced the engine was lifted into place fully assembled, except for the connection to the fuel tank and return. All that fuel stuff is CRAMMED in there.

    It's funny too that while I get what a vacuum reservoir does, I didn't fully understand why we need one on a 5th gen. The only vacuum operated component is the flapper solenoid, but you can forget that vacuum only happens on a down stroke, which means it will pulse. Even with just one little thing relying on engine vacuum, you need to even out the pulses.

    Jose
     
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