Help!!! BGF motor won't fire up

Discussion in 'General Questions' started by bilboby, May 20, 2010.

  1. bilboby

    bilboby Member

    After a flawless return ride from Paris yesterday evening i decided to ride out a bit further this afternoon but alas when pulling the Pull Cord the engine wouldnt start, unusual given it was working fine before i switched it off last night. I've checked the SP and the tip end was covered in black oil along with minor residue on the thread hence i cleaned inside the thread space on the motor and replaced the SP with the original stock type but still getting no power. Any help on resolving this issue would be much appreciated as now i've got the MB bug i don't want it to end suddenly.

    Cheers and good riding

    NB: I've checked the electric's and all is 100%.

  2. AussieSteve

    AussieSteve Active Member

    You say you've checked the electrics. How, exactly? ie. Did you measure the magneto voltage? How did you check the CDI?
    Lay the plug on the head then spin over the motor and check for spark.
    I wouldn't bother with the stock plug. Buy a new NGK B6HS.
    It sounds like your fuel/air mixture is a bit rich, too.
  3. bilboby

    bilboby Member

    Cheers Steve,

    Your suggestion for the fuel/air mix being a bit rich is spot on and if so i take it that the motor would need to be taken apart and cleaned? If so then atleast it'll help me understand the basic's of how the motor works + help in doing future repairs.

    Cheers & good riding
  4. AussieSteve

    AussieSteve Active Member

    No, there's no need to pull the motor apart. The rich mixture might have caused a bit of extra carbon to build up, but that won't hurt anything.
    To make the mid-range mixture leaner, (less rich), you could try lowering the carb slide needle by one notch, (raise the clip one notch).
    If the problem is at WOT, a slightly smaller main jet might be needed.
    Dellorto PHBG carby main jets are suitable.
    (DellortoDirect in the US, OzMiniMoto in Australia, ??? in France.)

    This thread might be useful:- NT Carb Tuning Basics

    Let us know how you go with a new plug and with testing for spark.
  5. bilboby

    bilboby Member

    Thank's Steve for showing the link to your post's much appreciated. I certainly will let you know how i get on with the repair but i won't beable to reply until next week as tomorrow Friday the Wife & i are off over too stay with some friends over in Western France (South Brittany) for a long weekend. Pity the MB isn't running otherwise i'd of taken that along for riding along the sea front. Oh well never mind, maybe another time?

    Cheers and good riding