lost power

Discussion in 'Motorized Bicycle General Discussion' started by datonamanmike, Jul 24, 2008.

  1. datonamanmike

    datonamanmike New Member

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    i was leaving my house this morning and when i started up my motor i relized i didnt turn on the tail light so i stoped
    the motor poped (kind of a backfire) and stalled
    now its harder to start takes longer to get up to speed
    and i feel air coming from the screws on the left side of the motor
    did i blow this thing up already ???
    it still runs but not as good
    any help is welcome and thanks in advance
    by the way 2 stroke china kit from boygofast
     
  2. Jemma Hawtrey

    Jemma Hawtrey New Member

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    from the description it *sounds* like a gasket problem - if by screws on the side you mean on the cylinder or the side plate on the crank.

    Two strokes use the crankcase as a pressurized part of the fuel system - if pressure is lost or reduced then the engine will not run as well..

    I would suggest having the head and cylinder off the motor and checking the gaskets for leaks - that will show up fairly readily.

    there might also be a problem with a broken ring or circlip as well, although I find it a little strange in both cases that you would have been idling when it had this problem..

    hope that helped...

    Jemma xx
     
  3. datonamanmike

    datonamanmike New Member

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    thanks for your reply Jemma

    it was more like as i slowed down to stop the motor stalled as it stalled it kinda poped (like a back fire )

    guess im taking off the head and cyclinder
    will i have a prob getting the rings back into the cyclinder ?? will i need a ring compresser ??
    thanks
    the air does seem to be coming from the side plate on the crank.
     
  4. Jemma Hawtrey

    Jemma Hawtrey New Member

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    It does sound more like a gasket problem, if you werent gentle coming of the power you might have gotten a suck back effect that would have momentarily raised compression and popped a gasket somewhere..

    As far as the rings go, it doesnt sound like that is the most likely cause, unless you have been hearing odd noises since as well as the drop in performance.. if a ring has broken or unseated and slammed into one of the ports you would definately know about it sound wise..

    The fantic TI bikes used to demolish rings on a regular basis in just that way - you'd hear a nice tinkling noise and bits of ring would be spat out of the exhaust - at which point the bike wouldnt manage more than 40mph. They were only a 50cc producing 6.5hp through a 6 speed transmission making 65mph so they had excuse for being sensitive - although if you used the Iron cylinder from related bikes such as the fantic GT that would solve the problem.. apparently they were one helluva moped...

    Jemma xx
     
  5. datonamanmike

    datonamanmike New Member

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    so should i just replace the side cover gasket or should i go ahead and do the cyclinder and head gaskets too ??

    no noises like rings rattling
     
  6. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    First check you head nuts for tighteness, they may just be loose.
    Do you see oil or residue of oil leaking from the base or between the head/cylinder?
     
  7. datonamanmike

    datonamanmike New Member

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    the head bolts are tite

    iv had a tiny leak from the base of the cyclinder
    from day one

    there is a leak in the side cover and i feel air getting out at the screws in the side cover

    if i take the cyclinder off will i need a ring compresser to put back together ??

    and can i make new gaskets for the cyclinder and head
    or should i order some from one of our fine venders ??
    thanks
     
  8. Joshua

    Joshua New Member

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    I've had a small oil leak from the lower gasket from day one too. I've been curious if I needed to pull the head and make a new gasket but it seems like it isn't causing a problem. but I know it probably will some day. how hard is it to get it all back together after replacing the lower gasket. oh and my bolts are tight.
     
  9. misteright1_99

    misteright1_99 New Member

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    You wont need a ring compressor, but just note the small alignment pins in the piston ring slots, where the ends of the piston fit...You should get or make new gaskets and not use the old ones, at least for the base gasket, too much work if it doesnt reseal correctly.
     
  10. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    If you're feeling air from the side cover screws... you might have blown a seal on the side of the crankshaft?
     
  11. Norman

    Norman LORD VADER Moderator
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    I agree if its leaking out of a side cover take the cover off and see if the seal is leaking which can really raise jell with the engine. somewhere on here I've posted the seal sizes you can't repair a leaking seal but you can replace a leaking seal.
     
  12. datonamanmike

    datonamanmike New Member

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    where can i buy this seal ???
    is it real hard to replace ???
    i think this is the prob
     
  13. datonamanmike

    datonamanmike New Member

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    got my new crankshaft seal yesterday
    installed it and it seems fine now
    no more air getting out on the chain side

    i think i need a new plug little sputtering
    going on as it warms up

    thanks venice boy you were spot on
     
  14. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Thanks for the update and resolution of the problem.
     

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