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2 stroke problem

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by gre03, Sep 16, 2015.

  1. Hi, I'm in the process of building a motorized bicycle but am having troubles with the motor. Its a 2nd hand 'rocksolidengines' kit and it won't turn over.

    So i'll try my best at explaining the kickstart procedure:
    1. put a pedal to the front position
    2. when kicking down, this turns the gear on the RIGHT of the back wheel
    3. this turns the gear on the LEFT of the back wheel
    4. which in turn is connected to the motor and it should the piston etc
    the trouble i'm having is everything works but i put a huge amount of force into the pedal and the piston moves once and then the pedal won't move any more, with the sparkplug out i could hear it turning a few times but with it in it just turns once and then jams.

    I'm new to engine mechanics btw. Any ideas?
    Thanks


     
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  2. Have you completed the installation?
    Put in fuel and two-stroke oil?

    I dunno this kit, but, in the old days with motorised push bikes, you basically rode the push bike along, then operated the clutch or engaged the drive to the motor so it would start, as you were traveling along.

    You didn't "kick start" the motor, then start the bike moving from the motor.
     
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  3. turns out you were entirely correct. initially it turned over but didn't fire, a few twists of the throttle to lean things out and she fired up. ran really odd, so i'll have to tune it but don't have any experience tuning 2stroke. wish me luck

    oh and also dropped the spark plug, which bent the top bit. now i need to re-gap it after i found out the gap. is there a standard gap? i read somewhere 0.6mm?
     
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  4. Again, back in the old days....the default plug gap was the thickness of the card making up a cigarette packet.

    Tuning 2-strokes IS a black art, so I do wish you luck with it.
     
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  5. I wouldn't call it a 'black' art ... more of a hazy blue one. I didn't notice a full blown expansion chamber in the pics so it shouldn't be TOO crazy to tune. The standard deal of getting the float level to spec and using the idle-drop method of tuning (google will turn up videos of how, it's not difficult) will get you most of the way there.

    Looking at the kit in the link, that's just a NGK spark plug. Should be over the counter at most auto parts shops, or bike shops. Probably about $5 a throw. I'd be inclined to replace any plug I dropped regardless of how it looks.

    Be careful with the two stroke fuel mix. Too much oil is better than too little ... within limits.
     
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  6. Standard gap on all the 2 smokes I owned was 25 thou. Yep cigarette packet cardboard.
    Keep 2 spare gapped plugs in your sky rocket, every time you ride it.
     
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  7. Brand new 2stroke i think its best to add extra oil to the mix for the first tank .
    It will have heasps less power but will help prevent premature wear
     
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