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  1. #1
    RC Competitor
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    Engine RPM increases when i lift off the throttle

    My revo 3.3 seems to be tuned fairy well.
    Take off, idle, top speed, acceleration are all good, but i'm still having a irritating little problem which i cant seem to solve.

    If i accelerate at full throttle the revo moves fine, but just as i let off the throttle, the RPM of the engine increases alot before it slows down.

    It doesnt sound like an engine tuning problem, as i've played with the TUNING alot. It sound like more of a mechanical sound. Kind of like when you driving a manual car, and suddenly downshift 2 or 3 gears while you still moving relatively fast. The mechnical energy/ or the RPM of the wheels and drivetrain filter back and increases the RPM of the engine.

    Anbody had this problem before?
    Any idea on where to start looking to solve this problem?

    Could it be with the slipper clutch being too loose or too tight?

  2. #2
    RC Turnbuckle Jr. icepick832's Avatar
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    To lean on the low end is what does it to me. The down shift sound is detonation. Usually a loose slipper will also do it at take off, and to tight you will see the resistance as you accelerate, and its a more consistent gear whine.

  3. #3
    RC Champion
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    if hitting the breaks doesn't stop the RPM increase you are way to lean. This is one of the tell tale signs of running lean!
    V-Spec Revo, UE EXT Thunder SM

  4. #4
    RC Turnbuckle Jr.
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    Sounds like 2 different problems..if you let off the throttle and it revs higher and your lsn is good as you described, it's an air leak.. If you let off the throttle and as the truck slows down the motor slows down with it, it's probably a weak clutch spring..
    Keep flex'in those forum keyboard muscles.

  5. #5
    RC Champion
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    Quote Originally Posted by got_nitro
    Sounds like 2 different problems..if you let off the throttle and it revs higher and your lsn is good as you described, it's an air leak.. If you let off the throttle and as the truck slows down the motor slows down with it, it's probably a weak clutch spring..
    Air leak still makes it lean. As far as the weak spring the only way this is possible is if the idle of the motor is to high. Still they pretty much have to be broke for the clutch pads to stay engaged. I've never heard of a motor winding down with the truck because of a broken spring, And I've broken the 3 of my trucks springs this season and this didn't occur. I still even drove them the only problem is when you stop the wheels from turning the motor naturally stops too........
    V-Spec Revo, UE EXT Thunder SM

  6. #6
    RC Turnbuckle Jr.
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    Quote Originally Posted by newb-rookie
    Air leak still makes it lean. As far as the weak spring the only way this is possible is if the idle of the motor is to high. Still they pretty much have to be broke for the clutch pads to stay engaged. I've never heard of a motor winding down with the truck because of a broken spring, And I've broken the 3 of my trucks springs this season and this didn't occur. I still even drove them the only problem is when you stop the wheels from turning the motor naturally stops too........

    Great^^^!


    [QUOTE]
    It doesnt sound like an engine tuning problem, as i've played with the TUNING alot. It sound like more of a mechanical sound. Kind of like when you driving a manual car, and suddenly downshift 2 or 3 gears while you still moving relatively fast. The mechnical energy/ or the RPM of the wheels and drivetrain filter back and increases the RPM of the engine.[QUOTE]



    Then it must be the flux capacitor..

    j/k lean or air leak then... lol
    Last edited by got_nitro; 09-15-2008 at 06:24 PM.
    Keep flex'in those forum keyboard muscles.

  7. #7
    RC Racer
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    Apr 2008
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    check your clutch also.. I've had this happen a couple times...

  8. #8
    RC Champion
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    also may wanna take a look at your linkage as well...your radio may not be centering the servo like it is supposed to either. when setting your idle remove the air filter and check to see that you have a gap about the width of a credit card with the throttle closed.
    zip ties & duct tape,a racers most important tools

  9. #9
    RC Competitor
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    I tried richening the LSN but with no luck, it still does the same thing.

    now what do i do, im stumped!

  10. #10
    RC Champion
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    Aug 2006
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    Here is some very good advice from Tim Roberts on the Revo-World forums. I hope it helps, I know it helped me.

    http://www.revo-world.com/forums/sho...16&postcount=2
    send $10 at paypal.me/Ray1964

  11. #11
    RC poster
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    Nov 2019
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    3

    Yes my revo 3.3 as soon as I lift off the throttle it seems like it down shifts to 1

    Quote Originally Posted by shahin View Post
    My revo 3.3 seems to be tuned fairy well.
    Take off, idle, top speed, acceleration are all good, but i'm still having a irritating little problem which i cant seem to solve.

    If i accelerate at full throttle the revo moves fine, but just as i let off the throttle, the RPM of the engine increases alot before it slows down.

    It doesnt sound like an engine tuning problem, as i've played with the TUNING alot. It sound like more of a mechanical sound. Kind of like when you driving a manual car, and suddenly downshift 2 or 3 gears while you still moving relatively fast. The mechnical energy/ or the RPM of the wheels and drivetrain filter back and increases the RPM of the engine.

    Anbody had this problem before?
    Any idea on where to start looking to solve this problem?

    Could it be with the slipper clutch being too loose or too tight?
    I have tried tuning changing tires and it seems like it is down shifting into 1st as soon as I lift no matter how fast i'm going

  12. #12
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    Nov 2019
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    It's not the slipper because I don't have one

    Quote Originally Posted by icepick832 View Post
    To lean on the low end is what does it to me. The down shift sound is detonation. Usually a loose slipper will also do it at take off, and to tight you will see the resistance as you accelerate, and its a more consistent gear whine.
    It can't be too lean on the low end I do a pinch test regularly and it revs up and dies at 3 almost 4 count it runs awesome everything is awesome except that downshift if I turn the idle down to where it's just too low to stay running by its self it stops revving up but I have to be careful not to let it die

  13. #13
    RC poster
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    Nov 2019
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    Why does hitting the brakes stop it

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