80cc engine wont start and hasnt yet

Discussion in '2-Stroke Engines' started by shane irl, Feb 24, 2010.

  1. shane irl

    shane irl New Member

    i built my bike on monday and it hasnt started yet .the spark plug is sparking and its gettin petrol and air compression is good i think maybe its my fuel mix its a bit rich and harder to ignite.please help with this problem

  2. retromike3

    retromike3 Member

    I usually have to start it by putting the choke on for a bit and then put the choke down and try it again. it should start right up. remember to keep the mixture low before its broken in. (about two tanks)

    Mike Frye the bike guy
  3. shane irl

    shane irl New Member

    you mean run it rich?
  4. shane irl

    shane irl New Member

    no didnt work .....how do you know if you blew a magneto?
  5. retromike3

    retromike3 Member

    if you take the spark plug out and lay it on the head with the wire connected (on a bike stand) then rotate the crank and pop the clutch there should be a spark.

    if no spark then its time to check your electrical system.
  6. shane irl

    shane irl New Member

    i checked it there and its sparking ...... what could it be if it is sparking and is getting petrol?
  7. Crobo

    Crobo New Member

    does it turn over at all? or is it just the popping from peddling. make sure the carb is correctly assembled. make sure the idle screw isout far enough. make sure the carb is pushed onto the intake manifold all the way.
  8. AussieSteve

    AussieSteve Active Member

    'Turning over' and 'firing' are two entirely different things. Popping?

    'Idle screw out far enough?' Turning the idle screw out will slow the engine at idle, but won't affect starting.

    Shane, if it's got spark and fuel, it could be too much or too little fuel.
    Mike didn't necessarily mean 'run it rich', just one attempt at full choke, the engine might fire and cough once or twice, but won't run.
    Then, turn the choke off and try again - it should fire up.

    You are aware, I hope, that the choke is 'off' when down and 'on' when up?
    (Mike sort of mentioned this, but you might not have noticed.)

    Keep us informed,

    ... Steve
  9. GearNut

    GearNut Active Member

    I always think of the choke lever as a light switch. Up is on, down is off. It's easier that way.
    When you take out the spark plug after trying to start the engine is it wet with fuel or dry?
    Wet would indicate that the carb is giving out too much fuel, and dry...well, I think you can figure out that one.
    If I am not mistaken, the initial setting for the idle speed screw is 3 1/2 turns out from all the way in. That will at least get the slide in a position to get the engine running and from there you can adjust the idle speed screw to obtain a good idle speed. Adjust it after the engine is warmed up well. In is faster, out is slower.
  10. AussieSteve

    AussieSteve Active Member

    Up is on, down is off - works for the choke and for power switches in the US, but here, down is on and up is off.
    I put a bit of thought into this once. Your system is definitely more sensible. Let's say a broom is leaning against the wall and falls over, hitting the switch. In the US, the switch will turn off. Here, it will be turned on. Potential disaster.
    This goes for anything 'gravity-driven' that might bump a switch.

    Shane, I just noticed your previous post about the slide-needle falling out. Are you sure that you have it in place correctly, with the spring pushing down on the 'c' washer on top of the needle's 'c' clip to hold it in place?

    ... Steve
    Last edited: Feb 26, 2010
  11. Hajuu

    Hajuu Member

    I found it easy once I took the air filter off my carb the first time, it was obvious how it worked.
  12. shane irl

    shane irl New Member

    i know how to work the choke ......the plug is getting wet but it should still at least splutter even if its flooded....the slide needle is in place and back together again....i already rebuilt the carb and pushed it on all the way....it is burning a bit of petrol but it just sounds as if it is turned off. it doesnt cough or splutter it just turns over ....i think the kill switch might be faulty but i dont know?
  13. AussieSteve

    AussieSteve Active Member

    Didn't you say that it was sparking OK? If so, that rules out the kill-switch.
    (You have tested for spark?)

    Not real sure what you mean by re-built the carb.

    Also, just because the carb is pushed right on doesn't mean that it won't leak - in fact it probably will. Do a search on this sometime.

    Even if it leaks at the inlet a bit, it should still run.

    If it sparks OK, try starting at several different choke positions. That should rule out a lean mix from an inlet leak.
    If it still doesn't fire, it's probably a rich mixture, for one reason or another. Are you sure the slide needle is correctly fitted? If the 'c' washer isn't holding it down, the needle can rise into the slide, enriching the mixture heaps.

    ... Steve
  14. shane irl

    shane irl New Member

    i know what way the choke goes and its getting petrol,air,compression and spark ....i think it coul be that the mag or cdi isnt strong enough to spark under compression because it does spark when out of the engine but when im trying to start it it sounds like thers no spark
  15. jsw5620

    jsw5620 New Member

    Maybe drain the fuel from the bowl, and then turn your gas on from the tank just for a second to get a little fuel in the bowl and shut it back off and then try to start it? I know on one of mine, it can take quite a bit of peddaling to get it started.
  16. shane irl

    shane irl New Member

    alrite thanks il try that
  17. shane irl

    shane irl New Member

    i got it started today...it was a faulty cdi....but it still isnt running rite....it lacks power and struggles up hills and cuts out sometimes it could be the carb but im not sure.
  18. retromike3

    retromike3 Member

    patience, is a virtue.

    It seems to me that my motor will not get enough power until it gets warmed up. this may take over a mile or two. After a bit my motor seems to take off and then it runs like a top, But before that it is quite sluggish and dies often. If you can get by this warm up period you will really get to like it.

    Just a thought.

    Mike the bike guy:D
  19. Hajuu

    Hajuu Member

    There's many different climates in the world, I think it's just a matter of tuning the stock setup for your conditions.

    Also, you will need to use some choke if its too cool outside when warming up, and turn off as it warms.. However you might not need a full on/off, you might need a subrange. Too much or too little in the wrong conditions will cause it to die often and lack power.

    To me, if its running to me it really shouldnt be 'dying' while moving unless you pull the clutch in, which probably means the idle screw needs to be adjusted.
  20. retromike3

    retromike3 Member

    I agree, but

    From the bit of riding I have done I have found that the idle seems to change over times and conditions. It is not always easy to adjust your idle every time conditions change. Like today when I went for a short ride the engine staled twice when I came to a stop sign, But I knew it was cold and about two miles later it was idling perfect. On some carbs they make a adjustment for the idle with a remote lever. Others have a barometer system built in to automatically change the adjustment, but I seriously don't think you would want to pay as much for the carb as you would for the engine.

    Mike Frye the bike guy
    Last edited: Mar 1, 2010