Greetings,need help with new motorbike

Discussion in 'Introduce Yourself' started by chuckieserre, Jul 24, 2010.

  1. chuckieserre

    chuckieserre New Member

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    Greetings,I ama medical technologist,but have built some of these bikes,now working on a 2 stroke 48cc grubee on 1 0 speed cruiser bike (columbia,big tires),the problem is that as soon as it starts(which does most of the ime-if gas ,ticker and choke are into place),but then it starts speeding up in such an incremental-logarithmic way ,that if leave it running -nohing -would stop the engine,including the choke ,the gas valve ,the iddle screw,the clutch OR THE KILL SWITCH. I tried this engine on a bike stand,but if running it would have been disastrous,since I could only pull the spark plug to stop it.Have taken apart carburator and nothing seems runs(only one time lef it overnigh and reservoiur got overfilled wih gas ,that came out of air filter.Now still wondering if the float,carb or somehing else is involved.Hope someone can help me ...:)
     
  2. wheelbender6

    wheelbender6 Active Member

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    Welcome to the forum. Check for a stuck throttle cable. Make sure the slide in the carb comes all the way down (remove the air cleaner to see that). If that checks out, it could be an air leak on the intake side. Put "air leak" into the site search window and see how others solved it.
     
  3. KCvale

    KCvale Active Member

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    Fix that first!
    Do you have an OHM meter or 'Continuity Tester' ?
    You can get a multi-meter at Harbor Freight or Radio Shack for $5.
    This a cheap tool with many uses so get one ;-}

    Set it to the 2K-20K ohm scale and hook up the leads to your kill button wires.
    When you push the kill button it should pretty much zero out meaning the button works.
    If not you should get some other button to use.

    If it does, and you hooked it up like the kit indicates, one wire to the motors white wire and the other to the frame, put your probes between the wire you hooked to the frame and your spark plugs screw or any motor bolt. If it doesn't zero out then your motor is not grounded to the frame.
    You can either tie the frame ground kill button wire to the motors black wire, hook it directly to a motor cover bolt, or ground your motor to the frame.

    If you didn't take the slack out of the throttle cable with the cable adjusters on the throttle itself and the top of crab, what tends to happen when you give it throttle and then lay off it the outer cable shield will tend to pop out of the top of the carb hole and hang up on the top of it thus acting the same as turning the throttle.

    The inner carb slide can get hung up for no apparent reason too.
    I have a brand new carb that does that on the bench now and can't see why, but as wheelbender said, take off the air cleaner and work your throttle from off to full and back slowly and verify it always goes all the way back down.

    If not then are a few things you can for that but lets narrow the problem before tackling the help for what it is ;-}
     
  4. chuckieserre

    chuckieserre New Member

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    Greetings,thanks for help,I used meter to check resistance and the bicycle paint might have been acting like an insulator,so now the kill switch is working,the throttle is not working properly and it pops out of reservoir,need to know how to deactivate it,since the handlle rotator was not turning and had to reattach it with cement,but I examined with my microscope(microbiological) the deposits on the spark plug,more tha 50% are carbon deposits which make me think that they where caused by the engine running RICH on gas NOT LEAN or with a lot of air.Any suggestions ???:)
     
  5. KCvale

    KCvale Active Member

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    You lost me there. Do you have some pics?
     
  6. chuckieserre

    chuckieserre New Member

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    Greetings,here is a pic of the attachment to the thottle (that always comes out),I had put some silicon to seal possible leaks,but realized that for some reason the engine is getting too much gas ,do not know how to deactivate the thottle in order to adjust the iddle speed....:)
     

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  7. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Sounds like your carb is assembled wrong, and you have an air leak. As for checking your plug with a microscope....I can't help you there.
     
  8. stevolandis

    stevolandis New Member

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    To fix air leaks, make sure the intake tube is bolted tight, put an o-ring between the carb and intake tube, make sure your carb is assembled right, everything tightened down.

    To adjust idle, let the throttle all the way down(if it works yet) and turn the screw on the left side of the carb out a little, that will lower the idle, in will up the idle.
     
  9. chuckieserre

    chuckieserre New Member

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    Greetings,thanks for all help, the best advice was the one about the thottle cable popping out,this actually stopped the engine from constant acceleration,at the sametime the needle elevation permitted the iddle speed adjustment.There might be little leaks but looking at the spark plug carbon deposits make me think the main issue was to much gas from thottle speeding,and not as much airleaks,I put an oring(made/reinforced with silicon).I still need to understand or get diagram of the internal workings of the thottle handlebar since I had to cement it with jb weld to make it work,and do not know if I might need a new....Thanks very much for great help..:)
     
  10. city of angels

    city of angels New Member

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    my best bet is just buy a brand new carb and a new throlte asembly
     

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