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Thread: Fixed the vacuum leak now I have a 3K RPM idle

  1. #1
    apriliaforum prov-nov OnlyLookItalian's Avatar
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    Fixed the vacuum leak now I have a 3K RPM idle

    So a little back story. I bought this 2003 Tuono a couple of months back. It came with a vacuum leak and an idle of about 1800 RPMs. After replacing the intake flanges, some hoses, and flattening out the bent throttle plate I have fixed the vacuum leak. However, after putting everything back together the bike shoots up from 1250 RPMs to 3000 RPMs after the warmup cycle. My next steps are to disconnect the TPS to see if that is throwing it off and double check the throttle cable connections at the throttle body are set correctly. I double checked that last part before buttoning everything up but I could have overlooked something. The bypass screws are set to 1 and 1.5. The Trimpots are both at the 12:00 position. Anything else I should check?

  2. #2
    apriliaforum expert kzmille's Avatar
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    Have you readjusted the idle speed?
    This is America. Use your turn signals or WE WILL KILL YOU - remember Sandra Bland

  3. #3
    apriliaforum prov-nov OnlyLookItalian's Avatar
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    Quote Originally Posted by kzmille View Post
    Have you readjusted the idle speed?
    It’s backed off all the way.

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    apriliaforum Junkie
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    Bent throttle plate... You should sync cylinders or buy new throttle body. Plates needs to be perfect...

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  5. #5
    apriliaforum expert kzmille's Avatar
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    Yeah, I would definitely suspect that if it was bent.
    This is America. Use your turn signals or WE WILL KILL YOU - remember Sandra Bland

  6. #6
    apriliaforum prov-nov OnlyLookItalian's Avatar
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    Yeah, I was shocked when I saw how bent it was. It’s back flat now. At least as flat as i can get it without using a surface plate and a dial indicator. I got the idle down to 1250 like it should be. However, I’m way down on power. When I get to school tomorrow I’m going to sync the throttle bodies and hopefully use an EGA to get this girl back in shape. I am happy about the smooth idle and being able to cruise at low speeds like a normal human being.

  7. #7
    apriliaforum expert kzmille's Avatar
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    How did it get bent/
    This is America. Use your turn signals or WE WILL KILL YOU - remember Sandra Bland

  8. #8
    apriliaforum prov-nov OnlyLookItalian's Avatar
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    Quote Originally Posted by kzmille View Post
    How did it get bent/
    It was either a strong backfire or it was on purpose. I’m leaning towards the latter because the backfire should have caused the plate to open instead of bending based on the side that was bent. Maybe done for sound during idle. As soon as I flattened it out the idle got much quieter, but the bike seems to like it better. Sounds much smoother.

  9. #9
    apriliaforum expert kzmille's Avatar
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    I have a hard time believing anyone would do that on purpose. The only other instance of this I remember occurred when the plate screws came loose.
    This is America. Use your turn signals or WE WILL KILL YOU - remember Sandra Bland

  10. #10
    apriliaforum prov-nov OnlyLookItalian's Avatar
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    Quote Originally Posted by kzmille View Post
    I have a hard time believing anyone would do that on purpose. The only other instance of this I remember occurred when the plate screws came loose.
    They were snug when I removed the plate. Whoever did it had to know it. But it’s fixed now. However I am having a time getting the throttle bodies synced up. There are a lot of variables to change.

  11. #11
    apriliaforum Member
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    I just noticed in your other thread, that your Factory Pro chip appears to be the version for enlarged (54mm) throttle bodies--considering this was an aftermarket service, perhaps KZ is correct about the plate loosening up at some point?

    As I'm sure you've discovered, those butterflies have to be perfect for good idle quality. Years ago, I had to remove the throttle shafts on a set of the much maligned Zenith INAT carburetors for old MB and BMW six cylinders (actually an excellent device if tuned with care according to the service instructions). The backstory is irrelevant on this forum, though I recall spending many hours in a dark room with a flashlight carefully aligning the plates, then had to pull the carbs off the car a few times to make further fine adjustments. Misalignment can really screw with the fuel atomization at idle. Not to mention, you need them closed enough to bring the idle speed within range, but not so closed that they bind or score the throttle body...

    Finally (and I don't mean to state the obvious or preach to the choir) -- those butterfly screws should be peened with a bit of loctite

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