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Weird engine behavior

Discussion in 'Engine & Exhaust' started by Ice_2k, Jun 6, 2017.

  1. Ice_2k

    Ice_2k Senior Member

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    Hey guys,

    I'm having some really strange behavior with my 32cc DuneRunner. Basically, it's gotten more & more difficult to start it and after it does start, after about a minute or two the idle revs start going up. It starts up very nicely at 3500-4000rpm and then it goes as high as 8000rpm. The tank is vented, I checked. Sometimes just giving a squirt on the throttle and then letting it go and the revs refuse to come back down. Carb butterfly is moving ok. The really weird thing is this: I thought "what the hell, maybe the LSN got screwed up and it's running very lean?" and I tried playing with it a bit. When the car was idling at ~7000rpm, I turned the LSN clockwise (so, giving it even less fuel) and it choked on itself, the way it does when you give it a lot of fuel on the LSN. I'm confused, anybody got any ideas?

    Not sure if it matter but this is my setup:
    Stock 32cc
    Walbro WT1107
    JetPro exhaust
    JetPro silencer
     
  2. Phill

    Phill Active Member

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    Maybe an air leak?
    Where you been Ice?
     
  3. designed2survive

    designed2survive Senior Member

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    @Ice_2k

    Wow! Welcome back! Where have you been?

    I'm sure you have a spare carb laying around. May be try it on?
     
  4. Ice_2k

    Ice_2k Senior Member

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    Hey guys, good to be back, I'm impressed you remember me :) I had a lot of things going on in my life during the past year and really didn't have the necessary time to hang out on forums anymore. But now I'm back :p I think the DuneRunner actually spent more than a year tucked away in its storage place. This revs issue is probably its way of punishing me :))

    Getting back to the issue at hand, I will try to swap the WT1107 with the stock carb and see if that changes anything. I was thinking if there's a simpler test I can do before taking the car apart. Is there an easy way to check for an air leak?
     
  5. designed2survive

    designed2survive Senior Member

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    @Ice_2k

    Glad to have you back and hope all is ok.

    To detect air leak, spray WD40 around the carb while it's running. If RPM goes down, you have a leak.
     
  6. Ice_2k

    Ice_2k Senior Member

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    there it is! I remembered something about spraying something but couldn't put my finger on the details :D Thanks a lot, I'll try it in the weekend and report back.
     
  7. macandnews

    macandnews Junior Member

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    Hello,
    I think you need this:
    http://www.davesmotors.com/walbro-wt-499-wt-603-wt-668-carb-rebuild-kit-k20-wat.html
     
  8. Ice_2k

    Ice_2k Senior Member

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    Thanks, if it turns out to be the carb, I'll definitely get that. Or maybe finally pull the trigger on an OBR engine :p
     
    macandnews likes this.
  9. bravo71

    bravo71 New Member

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    everytime i have an issue the quick fix is a new plug. the amount of playing with the fuel mixture reminds me of a nitro car. shouldnt be like that. small turns real sensitive
     
  10. Ice_2k

    Ice_2k Senior Member

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    already tried a few plugs, that's not it. I actually didn't play with the screws at all since the first tuning it, just tried it now since this issue appeared.
     
  11. G-Man

    G-Man Junior Member

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    Hey man I have come to the conclusion that dirt gets pulled into the primer bubble inlet hole. I trashed a 990 carb in 6 months. So I found these team chase filters that bolt on to filter the incoming air. Here is the link... http://www.davesmotors.com/Team-Chase-Carb-Diaphragm-Filter-2701.html
     
  12. Ice_2k

    Ice_2k Senior Member

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    I actually already have one of these :D
     
  13. G-Man

    G-Man Junior Member

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    Oh great you are ahead of the game
     
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