Engine Trouble new build would like some help! no power then high revs at idle

Discussion in '2-Stroke Engines' started by wan37, May 27, 2012.

  1. wan37

    wan37 Member

    I have a new Z80BK bgf.I can get it running with the kill switch not connected.I'm running 16 t0 1 oil.New spark plug ngk b6hs and wire.Well here is the problem running bad no power and revs really high when trying to stop with clutch lever in.I checked float it's at 21mm and have a o ring in the carb which is a nt carb.The throttle needle is moving freely and in right, Idle screw is not screwed in very far.It revs to high to try to find a air leak.The throttle cable is not adjusted to tight either.The jets are in tight too,and clean.Any other ideas please tell me.Thanks

  2. Lunardog

    Lunardog Member

    This may be out there but is your float needle in place and the seat ok? If youve checked everything else all I can come up with is the bowl is overflowing and pushing fuel past the needle and up to the intake. Its a longshot but who knows.
  3. wan37

    wan37 Member

    Thanks good one to check.
  4. Al.Fisherman

    Al.Fisherman Active Member

    First of all do away with the 16:1 and go with 20:1 to start and after break in up to at least 32:1.
    Where did you hear about 21mm on the float? I never have.
    What position is the "C" clip on the needle?
    Umm no power, check the compression.
    You sure the carburetor slide is installed correctly?
    Don't overlook that you might have a vacuum leak.
    Remove air cleaner back out the idle screw, and look into the carburetor, and see if you can see the bevel in the slide. Making sure the slide is closing.
  5. wan37

    wan37 Member

    Al I read that on one of the forums about nt float at 21mm it said level with the jet.Thanks
    I look in the carb when I put the carb slide in it was in right but it would rest on the idle screw with bevel.So I took the idle screw out just to see if it would close all the way and it would not just a little very little gap from closing didn't think that would make it idle that much.
  6. Al.Fisherman

    Al.Fisherman Active Member

    As these engines don't always sit level, so goes the carburetor, you can't just go with the 21mm measurement as a standard. ??? maybe so is the carburetor sits level. Still check out the woodruff key.
  7. Krisma

    Krisma New Member

    I had a problem with fast idle, turned out to be the slotted washer on top of the throttle needle was slightly bent which held the needle off bottom. Also found that the needle itself was slightly bent with a tiny kink toward the middle of the length.
  8. wan37

    wan37 Member

    Thanks guys going to check carb slide needle again and I'll check the timing key way like Al said.
  9. wan37

    wan37 Member

    Okay what it does at this moment I turn fuel on and choke on or off doesn't matter.Start pedaling release the clutch motor turn over and it seem to be firing trying to start but as soon as you squeeze the clutch lever back for it to idle it dies so I have to keep pedaling with clutch lever out and keep pedaling and throttle all the way on.Then after a while it gets better running but it starts to rev very high to adjusted any thing. Any idea's please help.
  10. Al.Fisherman

    Al.Fisherman Active Member

    Is the plug wet?
  11. wan37

    wan37 Member

    checked the carb slide it in right.I'll check the plug tomorrow getting ready for work.I think you are right Al.I totally agree on fuel mixture will change that too.I noticed black stuff leaking from exhaust.
  12. motorpsycho

    motorpsycho Active Member

    it's possible that your carb body is out of round (where the slide goes in), causing the slide to stick in the bore.
    If this happens, it will never return to the bottom and you'll never get the idle as low as it should be.
    the heat from the engine will distort the bore of the carb even more.
    it is possible that when the engine cools, the carb contracts, making the slide fit tighter in the bore(if the bore is out of round). and them when it;s hot, the carb expands, possibly making the bore distort even more, and POSSIBLY letting air go around the slide as well as under the slide.
    I don't know, i'm just throwing ideas out there.
    you may even have an air leak at the top of the carb where the cap screws onto it.

    you will always get "black stuff" leaking from the exhaust no matter what fuel-oil ratio you are using.
    That "black stuff" is excess, unburned oil, and this is what eventually clogs up the exhaust.
    yes, 16:1 is too much oil, drop it to 20:1 and then 32:1 as al suggested.
    but even at 50:1 you will still get the "black stuff" coming out of the exhaust, but it won't be as much as when you run 16:1.
    if you even look at weedeaters, chain saws, 2 stroke dirt bikes, they all drip oil out of the exhaust.....it's what 2 strokes do.
    Last edited: May 29, 2012
  13. wan37

    wan37 Member

    Thanks motor that's really possible because I got 2 nt carb and one looks a little different the slots on one where it slides on the intake are longer that the other.I look inside the carb from the choke side and it looks like in should slide down farther.I will check out all the things again from here this afternoon and let you guys know.Thanks again.
  14. dorourke

    dorourke Member

    This might not be applicable to youre delima, however, with mine I had the same problem and found a cork gasket on the float bowl for the carb. Mine leaked like a siv and now waiting for a real seal to come in. Don't know if that will solve anything but I think with all the vibration of these little engines the cork probably breaks apart after a while.
  15. wan37

    wan37 Member

    Thanks true about cork gaskets a piece broke off when messing with other one but fixed.I went with a rubber material.If I can't get it lined out I'll buy another carb there around$15 so maybe the slide might close in side more.
  16. geebt48cc

    geebt48cc Member

    Yes, Al said it, PLUG WET/Sounds RICH MIX!!!!!!!!!!!!!!!!~ You've got to carry between lines there..............(No to much, but not to little)

    PS: Keep eye on that plug , because burning right, won't change........................
  17. wan37

    wan37 Member

    I put a new clean plug and a different nt carb plus 20 to 1 oil mixture and bam she started and idle perfect...Thanks guys