New Zbox 70cc - Working fine today, not now?

Discussion in '2-Stroke Engines' started by jonasquinn, May 14, 2008.

  1. jonasquinn

    jonasquinn New Member

    Hm, Ok, My zbox engine arrived yesterday, it was working today, and I rode it home from work. Had dinner, came back to play with it, and it's not going at all.

    Once I release the clutch to start it, the engine turns over, and sounds like it's going, but I think it's just that the motion of the bike is keeping it turning over.

    I did notice that the carb was flooding after each of these tries, but that was probably because the fuel wasn't igniting.

    I figure it's something electrical. So I took the spark plug out and looked at it while I turned the motor over, I didn't see any spark. Are you supposed to get a spark when the spark plug is out of the hole?

    Could it be that the magneto, or CDI ignition box has gone? Or is it simply the spark plug?

  2. Marktur

    Marktur Member

    You need to ground the plug against the head when checking for sparks...when it's screwed in, it's making that connection.

    Are you using a kill switch? If you are, see if you can bypass it. (I got rid of mine completely, and just use the choke to kill the an emergency, I'll just stop and pop the clutch to kill the motor.) You can also use a multimeter to check the switch: there should be continuity on both sides of the switch until it's pressed.

    ALso - make sure there's a good connection on the black and blue wires from the magneto to motor. This is actually the first thing to do.

    In regards to being flooded try to start it without the choke.

    You have good compression, and we'll assume that the carb works since you just rode it, so yes, it's more than likely electrical.

    Hope that helps!
  3. kgray

    kgray New Member

    double check your wiring. i did the same thing today and the wires going to the cdi had become loose. to get a spark, you have to ground the plug to something like the frame.
  4. impression

    impression Member

    make sure to put electrical tape around the connections as it can short/earth on the bike's frame as you ride along.

    also DO NOT use the included kill switch, just stall the bike to stop it, or you can unscrew the idle controll which will also stop it in the mean time until you get a proper toggle switch installed.
  5. jonasquinn

    jonasquinn New Member

    Yeah, I tried again this morning. Same thing. I disconnected the kill switch to be on the safe side. Wiring looks fine, put the spark plug back in. Went to turn it over, and ride, it gargles along but probably only thanks to the momentum of the bike. When i give it some throttle, it gargles a different sound, but still cuts out nonetheless.

  6. impression

    impression Member

    That's just a cold start mate, you ned to use the choke.

    that is the little lever on the carby that goes up and down. when going down a slight hill to start the bike pull it upwards slowly from the down position until you hear the bike pull along, you should also feel it, then after about 10 seconds with cruising like this push the choke all the way down as you give it a bit of throttle.
  7. jonasquinn

    jonasquinn New Member

    Ok, Impression, I took your advice. I rode the bike up around the corner, and tried it about 5 times coming back, as it's all a slight down hill. On the 4th go, I got one pop, but that was all.
  8. impression

    impression Member

    are you pushing the little button to let fuel in the carby for a good 3 seconds before you start ?


    button 3 secs

    ride bike for a bit with choke on adjusting choke to right spot, giving it a bit of fuel/rev to warm up.

    then when bike looks to be going a bit put the choke all the way down into off position and all should be sweet
  9. fatboy67

    fatboy67 Member

    The float might be sticking. You should turn the petrol off each time you finish riding. try tapping the carby bowl with the end of a screw driver, give it a good tap. The full lock on the choke and try with just a slight bit of throtle. When it starts you may have to start backing off the choke. Mine was a pain. "The carby that is." I reset the float to stop the carby from dripping petrol all the time when idling. Anyway let us know how you go....
  10. Marktur

    Marktur Member

    Here in FL, I use the choke for the first run of the day...seems like after that, It won't run with it as soon as you hear your motor start to kick, pull in the clutch and turn off (push down) the choke. Also - don't open the throttle too much when trying to start it with the choke on.

    If no better luck, change the plug, if no better luck, change the magneto...make sure the screw on the carb is open 4.5 turns (full turns). Also - how much oil did you mix in with the gas?
  11. jonasquinn

    jonasquinn New Member

    Alright, those last few responses gave me some really good notes that I can use in the morning to have another shot.
    Tapping the carby, carby screw out 4.5 turns, 3 seconds on the little button (usually I just push twice).

    I mixed 16:1 with it. But, I got over excited, and couldn't find a measuring cup, so I mixed it in tank. Realised my mistake though, and shook it around like crazy before I started the engine. Though I doubt that's the problem, as I rode it around work, and home from work (2km) fine that day. Can't wait for tomorrow, another day, and the bad luck meter resets itself :D
  12. Marktur

    Marktur Member

    Good luck man, I'm having my own share of bad luck with flat tires...When everything's right, I was loving it...but in less than a week's time, I've had 3 flats, which is really making me question the reliability.

    Just goes to show ya...if it aint one thing, its another...
  13. Is that the recommended oil/gas mix by the manufacturer for the break in on that engine? Mine was 23:1 per instructions that came with kit. Also are you using fresh gas? I use a bit of Stabil in my gas tank and only mix 1/2 gallon at a time..
  14. Marktur

    Marktur Member

    I have a 1 gallon container. I filled it with fresh regular gase, then poured in about 4 oz/ of ProMix 2 stroke oil. I think it's happy with that. It's more oil than I use for the weedwhacker/edger, too.

    With fuels and mixes and break in routines, everyone's got an here's a rule of thumb that I use: make sure you can see exhaust come out (blueish smoke) - that's telling you that there's plenty of oil. This is also how I break in my RC motors. I am not running at full throttle except when I'm accelerating up to about 20 mph...then I back off. I'm on my second gallon...and no, I'm not getting crazy 120mpg, more like half of that, but I also think it's due to extra oil and that it's not broken in yet.

    Hope that helps,
  15. impression

    impression Member

    i'm using 16:1 fuel/Oil ratio.

    63ml oil per litre of fuel.
  16. impression

    impression Member

    hows the engine going now ?

    and are you in for the sydney meet ?
  17. jonasquinn

    jonasquinn New Member

    Ok, it's all fixed, and going beautifully :D.

    It ended up being the magneto. Reckon I could warranty it, since it was but a day old?

    And, what date is the Sydney meet set to be?
  18. MarcMotorHead

    MarcMotorHead New Member

    are you using the connectors that came withe the kit if so remove them and solder the wires together, I had a simmlar problem and that what I did and I have not had any problems since.
  19. impression

    impression Member

    14th June i believe, it's a saturday ?
  20. wheelsy

    wheelsy New Member

    take the fuel bowl off and check the jet for blockage check fuel bowl for contaniments if it doesnt work after that and you got your engine wet it could be magneto