Bike fires but wont stay started

Discussion in '2 Stroke Bicycle Engines & Kits' started by ninjaplatypus42, May 20, 2017.

  1. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    Everything was running fine and then this problem started. The bike will fire a few times and sometimes and can even get it to rev but as soon as i let the throttle go it dies. I've tried everything at this point. There's spark, fuel, no leaks. When testing the spark plug against the head no there would be no spark if i turned it slower but with a decent kick there was a strong spark. I don't know if this is normal i've never payed that much attention to how fast it needs to spin before spark is made.
     
  2. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,376
    Likes Received:
    35
    sounds like choke came loose and is staying on, but could also be main jet fell out
     
  3. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    Checked both of those everything's good.
     
  4. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,376
    Likes Received:
    35
    I've also seen that happen when slide was put into carb upside down.
     
  5. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    What do you mean by slide?
     
  6. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,376
    Likes Received:
    35
    little barrel thing in carb that cable hooks to
     
  7. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    Oh okay. No that's definitely in right.
     
  8. Slogger

    Slogger Member

    Joined:
    Sep 8, 2014
    Messages:
    545
    Likes Received:
    3
    Check your head nuts, then go right back to the carb.
    These things are almost always needing dirt cleaned out of a jet or a float needle's seat.
    Too much gas will do just like you describe. It could be flooding. Was the plug wet?
    Mine was running ok, I cleaned the carb for spring and it ran twice as good and started a lot easier. If I had to fix it quick, I'd clean the carb especially the fuel passages.
    Good luck to ya!
     
  9. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    Head is fine torqued down properly. I took the carb apart and it was spotless. The plug wasn't wet but it was pretty dark. I assum this is from all the failed starts though. Every 50 tries or so I take the plug out and air the cylinder out to make sure there's not un-burned gas sitting in there. I mentioned in the original post that I don't get spark unless I kick it pretty hard and get it turning a few times. Is that normal? I've never really payed attention to how fast it has to spin before spark starts occurring.
     
  10. Slogger

    Slogger Member

    Joined:
    Sep 8, 2014
    Messages:
    545
    Likes Received:
    3
    It should make a spark at walking speed. I hold it against the head and walk the bike forward and see it.
    Double check how your spark wire is clipped to the plug. My original end never would snap down right and was bent up. It can touch the plug but never runs right unless you hear the click of it going correctly into place. This gave me hours of trouble to figure out one time.
     
  11. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    I've got a shift kit so i have to turn the pedals to turn the engine over but walking speed sounds about right. I'll double check the wiring and test the connections.
     
  12. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,376
    Likes Received:
    35
    plug not wet after all that cranking means you're getting no fuel
     
  13. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    It is firing though so fuel is getting burned up. Basically i crnk on the pedals hard it sputters once or twice and then nothing. Most of the time there's no sputtering but enough that fuel would get burned I'd think. I took the carb apart and nothing was blocked or gooked up or anything. Fuel flows nicely out of the hose so there's no blockage in the tank. All needles and jets are in the right place. The spark connection is good and I'm testing with the kill switch unplugged. I really don't know what else to check at this point.
     
  14. Chaz

    Chaz Active Member

    Joined:
    Jun 3, 2012
    Messages:
    910
    Likes Received:
    36
    Are you getting fuel flowing with the carb bowl drain test?

    If you've had the carb apart it may be the float tang is upside down.

    Are you using the stock acorn head nuts?

    You may be getting a bit of fuel to fire a couple of times but not enough to keep it going. Like crassius said, if your plug is not wet after all the cranking it may be a fuel flow problem.
     
  15. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    Is the carb bowl drain test taking the screw out of the bowl and seeing if fuel flows? Ill check the tang but I just took it apart and this has been happening for awhile. I'm using normal lock nuts not the acorn nuts. Low fuel matches the symptoms I agree but I can't find anywhere that could be causing that.
     
  16. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    Float tang was/is not upside down.
     
  17. Chaz

    Chaz Active Member

    Joined:
    Jun 3, 2012
    Messages:
    910
    Likes Received:
    36
    Okay. Tang is good.

    Yes, that is the bowl drain test.

    Maybe raise the float a touch?

    These little beggars are fun when they run but boy, they can be irritating at times. Even more annoying when you find out it is a simple little thing that's holding you back.

    good luck
     
  18. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,376
    Likes Received:
    35
    did you do a compression test?
     
  19. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    And fuel flowing freely out of is what you want right? I don't have any way to measure psi but it's as hard to turn as usual.
     
  20. ninjaplatypus42

    ninjaplatypus42 New Member

    Joined:
    Mar 16, 2016
    Messages:
    117
    Likes Received:
    0
    Fuel flows strong out of the bowl drain.
     

Share This Page