50cc BGF motor won't rev

Discussion in 'Motorized Bicycle General Discussion' started by cburr, Aug 1, 2008.

  1. cburr

    cburr New Member

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    I am new to the website, just finished installing my first motor in a beach cruiser. Motor won't rev feels like it's hitting a rev limiter. Checked the carb, main jet is clear, moved the needle clip up and down no difference. I don't think it's carb. Has anyone experienced this, before i start ordering replacement electrical parts? Thanks in advance.
     
  2. Dave31

    Dave31 Moderator
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    Welcome to the forum

    Use some WD-40, carb clean or some water in a spray bottle and pray the manifold and carb area and check for a vacuum leak. If the engine RPM changes you got a leak.

    Keep us posted
     
  3. Norman

    Norman LORD VADER Moderator
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    Pablo ran into a problem kind of like yours his engine would start and idle but would not rev up. If you played with the choke while riding the bike you might be able to get it to rev but it was a real pain just to do.
    Pablo sent me the carb and I found that what he told me about how the carb was acting to be true so I started to go over the carb. I found that all I needed to do to get it to work right was change out the needle and slide from my carb to his and it would work so I measured his needle and mine and found that his needle was not tapered correctly I tapered his needle and tried it on my bike and it worked great so I shipped his carb back to him end of story. I don't know if this is correct or not but I think his needle measured 0.070 at the top by the clip grooves and 0.070 at the bottom so there was no taper. It should be around 0.070 at the top and taper to 0.068 at the bottom but I'm not sure of the 0.068 measurement and can't check it until I return back to Texas. so if you have a way to measure your needle this is where I start looking for your problem of not reving. If you find that the needle is not tapered be very careful if you try to taper it as very small changes will affect it big time.
     
  4. deacon

    deacon minor bike philosopher

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    the most frequent problem is the air leak but norman is the guru here so try the simple things and keep his advice in mind before you go buying stuff.
     
  5. jasonh

    jasonh New Member

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    Also I guess obviously make sure your throttle cable is properly adjusted, i.e. make sure there is no play in the cable - you twist the throttle and it moves the cable as soon as you start twisting. You can take the little slide out of the carb and check that it moves properly as well.
     
  6. cburr

    cburr New Member

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    Thanks for the imput, sprayed starting fluid around intake and base gasket no change, the needle did seem awfully flat i'll check the taper. Where do you suggest to buy parts? are all the 2stroke chinese engines pretty much the same? has anybody seen a piston installed backward?
     

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