Carby Running too lean

Discussion in '2-Stroke Engines' started by fatboy67, Apr 2, 2008.

  1. fatboy67

    fatboy67 Member

    Hi to all,
    Firstly before I start about my carbie, I had my first post talking about kill switches. I was wrong I thought that they would do what I thought would be obvious and just interrupt the power flow, but they don't they short out the magneto. I don't want to install a toggle switch so I'll just cross my fingers that I don't have any trouble with mine.

    Ok on my 48cc Zbox motor the motor runs well but even when it's hot you still have to have it at 3/4 choke if you move it from this position it will not idle and will run poorly. i have moved the needle to the richest notch, this doesn't seem to make much difference. I have checked for air leaks and I'm pretty sure there are none. I did have some trouble with the carbie at the start it would leak or drip petrol when idling I bent the brass forks down about 3mm to stop the bowl from flooding this has work as when I ride it now it doesn't leak. Because I only rode it once for about 20 mins and found out the carbie was leaking I took it home and made the adjustments to the float, but I think that on the first ride (before I made the adjustment to float) I was able to turn the choke off.
    Question could it be that I have made the bowl level to low and I need the choke to help suck more petrol through???
    At the moment having the choke at 3/4 it idles nicely and goes quite well, but if you bump the choke the motor will bog down.
    I hope this all makes sense I'm trying to write this my 9 month old daughter is sitting on my lap screaming as she is hungry
    Thanks Gilbert........
    Last edited by a moderator: Dec 15, 2015

  2. mean lean

    mean lean Member

    gday gilbert, had same issues with a motor from zbox.
    tried many attempts to solve issues with help from guys here. In the end i spat the dummy contacted warren at zbox and he was nice enough to send me a new carby at cost price. some friends of mine here in south australia put these together as hobby/bussiness theyve been getting a few carbys with this issue. one of them found lightly sanding the needle down resolved issue. I read somewhere here i think from mikey, could be wrong, a good tecnique is put needle in drill as you would put the drill bit then you get an even sanding. take it in baby steps as to thin is no good, good luck!
    Last edited by a moderator: Dec 15, 2015
  3. mean lean

    mean lean Member

    oh yeah, i think our zbox motors are refered to as "happy time" motors. might help to know.
  4. graucho

    graucho Active Member

    Fatboy, I have also got junk carbs (not zbox) Replaced them and the bike ran like a top. But before you do this,
    *disassemble the carb.
    *Spin the needle a few times between fine steel wool or a fine abrasive sink scrubbing pad.
    *Put the needle back to the adjustment notch where it was in the first place.
    *Make sure all parts (needle and float) move freely. (not binding on carb body)
    *Check intake Gasket for proper seal
    *Make sure bowl gasket isnt smashed, and put back together. Dont over tighten.
    *Screw "idle adjustment screw" in all the way.
    *Back out "idle screw" out 4 full turns to get you into close idle range.
    See if this helps before buying a new one.
    Last edited: Apr 2, 2008
  5. BSA

    BSA Guest

    I've heard of a similar problem before, I can't find the post. It sounds like the intake gasket is no good. Do a search on intake gaskets and you should come up with the goods.