Flapper valve operation (not about mod)

Discussion in 'Mechanics Garage' started by headshrink, Apr 22, 2018.

  1. headshrink

    headshrink New Member

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    I finally got my new-to-me 8th gen naked for deeper inspection and cleaning. It has about 4k miles, was purchased after 2yrs of sitting, and I believe everything is bone-stock with no user modifications. One thing I noticed when I turned the engine on with the tank up is the flapper valve remained open (I thought it would be closed at low RPM). As far as I can tell it is all hooked-up, with no inline plugs. Does it sound like something is wrong, or normal?
     
  2. Terry Smith

    Terry Smith Member

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    This sounds probably normal to me.

    Not exactly sure about the 8G but on the 5 and 6, the flapper is kept open at all revs in neutral, and only does the close below 5500rpm/open above thing, when in gear, with the clutch out.

    You should be able to pull the neutral switch wire off the terminal on the clutch housing which will fool the ECU into thinking it is in gear when physically it is in neutral, and that will allow you to safely observe the flapper operation at a standstill.
     
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  3. headshrink

    headshrink New Member

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    Good to know, THANKS!
     
  4. headshrink

    headshrink New Member

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    I finally got around to getting in there, and yes, the procedure is the same on the 8th gen. My flapper is not working. I can't figure out what component is responsible, but I pulled the vacuum line and placed my thumb over it. I felt virtually no vacuum when I rev'ed it. Not sure what to do next.....
     
  5. Lint

    Lint Member

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    Remove it
     
  6. headshrink

    headshrink New Member

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    Would rather know what's wrong.
     
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  7. Terry Smith

    Terry Smith Member

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    There should be a vacuum line from an intake port going to a one-way valve and then to a vacuum reservoir, then to the solenoid and then to the flapper. Simplest change would be if the flapper solenoid was simply unplugged, that would mean no vacuum signal ever reached the flapper. Otherwise you could have a defective solenoid, or a vacuum leak in a hose, but the latter would normally mean an odd idle as well.
     
  8. headshrink

    headshrink New Member

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    It was all plugged in, and I tested the solenoid per SM procedures (tested wnl). I'm stumped.

    I had this http://vfrworld.com/threads/rpm-bouncing-at-idle.55090/
    but the video is before it warmed up, and it's settled down a bit. So nothing is really obvious to me.
     
  9. Doorag

    Doorag New Member

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    Did you ever get to the bottom of this? I have exactly the same issue on mine, except someone has done the flapper mod and I wanted to hook it up again while troubleshooting another (different) problem. When I tested the vacuum hose - no suction at all. There's nothing obvious as to why it shouldn't be working.
     
  10. headshrink

    headshrink New Member

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    No, I haven't had it apart since.
     
  11. signal

    signal Definitely Not New Member

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    Either of you get to the bottom of your flapper issue? My flapper also is not actuating and I am going to track it down.
     
  12. headshrink

    headshrink New Member

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    I haven't.... no time to dig that deep. I also still have to get rid of my 500r.
     
  13. signal

    signal Definitely Not New Member

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    Ok, well, the logical thing for you to do once you get around to it, is to trace the sub harness that has the flapper solenoid on it. You can simply unplug the 10P connector (this is on a 6th gen I assume its similar on 8th), and pin out the harness. The solenoid has a Y/Bl cable and you should have continuity between it on both sides of the sub-harness. This is the cable you should also see 12V on (I realize you do not see 12V). The other wire in the solenoid is a Bl/W wire. That is ground. You should have continuity between Bl/W on both sides of the sub-harness. You should also see continuity between Bl/W and these other wires which are in the 10P connector:

    P/Bl Injector 4
    P/G Injector 3
    R/Y Injector 2
    P/Bu Injector 1

    This is when the bike is off. This is because when there is no power to the injectors they are at ground (Bl/W).

    Assuming the sub-harness is good, then you can check from the other side of the 10P connector (main harness), and check the continuity to the ECM:

    Y/Bl B3
    Bl/W A4

    If you don't have continuity between Y/Bl and B3 then there is an issue in the main harness. If you do have continuity, then for some reason the ECM isn't putting out 12V on B3, investigate, perhaps a bent pin or something........possibly a hosed ECM.
     
  14. headshrink

    headshrink New Member

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    This is helpful. Thanks for reminding me about this issue.
     
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