Trouble shooting the bicycle engine that won't start

Discussion in 'Motorized Bicycle General Discussion' started by deacon, Feb 21, 2008.

  1. dgoria5

    dgoria5 New Member

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    I checked the park plug wire and no spark. I don't think the clutch is slipping because i can feel the cylinder moving and the resistance, however i still find it strange that the motor whirrs when the plug is out and does the opposite when its put back in. Personallly i think its most likely an electrical problem, Is there anyway to individually test the CDI unit and the magneto?
     
  2. bgoates

    bgoates New Member

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    That is exactly what happened to me. When the plug was out I got spark and the engine turned over. However with the plug screwed in clutch was just loose enough to slip and not turn the engine over....tighter the clutch a little until it sounds like it is running when you peddle.
     
  3. deacon

    deacon minor bike philosopher

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    If you have no spark on the wire when it is out of the bike you have an electrical problem. If if sparks when the plug is grounded it is something else and the clutch is a good place to start looking.

    Try this before you do anything else... Unhook the kill switch. those things are notorious.. then see if you have spark. That is the easiest place to start.

    then check to make sure your plug wire is making good contact with the cdi. Mine didn't at first. It it isn't either of those check your plug to be sure it isn't dead. Those are all easy to check before you go trying to figure out the cdi or magneto.
     
    #23 deacon, Mar 23, 2008
    Last edited: Mar 23, 2008
  4. dgoria5

    dgoria5 New Member

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    Thanks alot everyone who helped, I've finally fixed the problem and she fired right up. After much doubt it ended up being something as simple as the clutch slipping. I tightened the flower nut and we're good to go. ^5
     
  5. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    You are welcome.
     
  6. deacon

    deacon minor bike philosopher

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    It is almost always something simple. I can remember my problems with the kit were all my own doing for trying to be too timid with it. Seems to be a rash of those loose clutches lately.
     
  7. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Hah - too true.....but when these simple problem kick your ass.....boy does it make one humble!

    It's interesting that I can clearly feel and hear the engine turn over vs. the clutch "slipping" so I would have nailed that one right away....then someone else will walk up to my bike and say "Your wangy is discombobulated...." and I've been dinking at it for weeks!! rotfl
     
  8. Norman

    Norman LORD VADER Moderator
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    I have a wangy recombobulater if you ever need to borrow it. I can show you how to make one out of cat poo and sawdust as well and some VOODOO. Now if I could get Bob to return my chicken bones he borrowed last week. He said something about the neigbhors dog and took off with the bones and a 1/2 gal. of alcohol.
    Norman
     
  9. Ilikeabikea

    Ilikeabikea Moderator
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    You gotta watch Norman when he goes to wanting to loan you his wangy recombobulator. He'll trick you. You gotta watch him all the time...........rotflrotfl
     
  10. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Want a hammer and some lube to make it fit? :(rotfl:D
     
  11. Ilikeabikea

    Ilikeabikea Moderator
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    Pablo do they make that kind of Amsoil???? Inquiring minds want to know..............rotflrotfl
     
  12. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    Thanks for the idea!! We do have vitamins for well, you know, male-ness!;)
     
  13. Norman

    Norman LORD VADER Moderator
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    You mean for baldness? rotfl Wait a minute YOU sell an oil for Captian winky?! What is this world coming to????!!!!:confused:
    Me and Rufus are going to the shop I need to refinish a coffee table.
    I'm shaking my head I can't believe it. I gotta quit these engine assisted bicycles.
     
  14. deacon

    deacon minor bike philosopher

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    And i thought that was called KY
     
  15. Pablo

    Pablo Master Bike Builder & Forum Sponsor

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    No just to keep the rumors down I don't have.......er..........sell that kind of lube.
     
  16. motorman

    motorman New Member

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    Does anyone know of an NGK, Bosch, Champion, etc.....spark plug replacement for the China made spark plug that came with my 80cc kit? What is the proper (recomended) gap? Thanks...(c)
     
  17. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    NGK B5HS gap it at .020
     
  18. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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  19. motorman

    motorman New Member

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    Thank you. Also, I am having some starting issues. Do you know what the head bolts should be torqued at? What kind of compression should the cylinder have? I am thinking I have reduced compression.

    There is plenty of fuel coming from the carberuator when the plug is in and ignition when the plug is out of the cylinder head. When I place my thumb over the spark plug hole and spin the engine there is some compression but not a whole lot.

    Tonight afterwork I am going to check to see if the keyway is broken or wobbled out. These engines are basic so it should be easy to troubleshoot.(c)
     
  20. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    I replied to your other post on compression. Make sure you don't have any air leaks at the manifold/carb and torque the head down. Take the plug out and turn it over several times to clear the cylinder. Then use 1/2-3/4 choke and pedal it up to 10 mph and let the clutch out.

    Keep us posted.
     

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