4 stroking at low speed

Discussion in 'Motorized Bicycle General Discussion' started by porter1, Sep 11, 2014.

  1. porter1

    porter1 New Member

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    I am a newbee, here is my problem. china girl 80cc wants to 4 stoke until 12 mph, the is no adj. on carb except idle speed. I don"t know what carb. I have all it says on is" speed". I have maybe 50 miles on the motor. I started to run 40x1 mix with Yamaha oil. is this normal or will it get better when it gets fully broke in? I know someone here can help. thanks.cvlt1
     
  2. Henshooter

    Henshooter New Member

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    The standard jets on the factory carbys are way to big IMHO usually .68 ,my suggestion is to go down to a .65 and see if that helps

    But we really need more info such as jet size the oil your running and the type of carby ( I suspect the NT )

    There can be only two main suspects in my oppinion and they are jet size and fuel mix .
    Being a newbie you can get somewhat daunted by the carby adjust but it's simple ,I always run in my motors at 25:1 and general running after breakin at 32:1 ,you should find if you are running the kit recommended mix ,swapping down to 25:1 should somewhat fix your four stroking issue ,40:1 for breakin is IMHO way way to low to be any good for the motor

    Try these and get back to us with your results

    Regards Hen
     
    #2 Henshooter, Sep 11, 2014
    Last edited: Sep 11, 2014
  3. porter1

    porter1 New Member

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    was running 25x1, was worse, the guy I bought it from said go to 40x1 now he already ran 1 tank of gas through it, I have ran 1 also, where do I get jets?
     
  4. SpecializedMountainMoto

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    Wait until u get at least 100 miles on it before u start messing with it, but I would go with a 24:1 mix until 100 miles
     
  5. crassius

    crassius Well-Known Member

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    300miles would be better before trying to tune it - the older speed carbs were about 2mm larger in the venturi than NT - didn't make them horrible on the standard engine setup, but they worked better with an expansion pipe - I currently see a newer ver of the speed carb being sold now, but don't know what has changed
     
  6. porter1

    porter1 New Member

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    ok, went with 32x1 mix, as the miles are going up the 4 stroking is getting better, also put in the proper heat range plug. It"s getting better every day, so I think I'm good to go. I must say though my Honda and Yamaha mopeds ran much smoother. those **** are hard to beat.
     
  7. crassius

    crassius Well-Known Member

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    Yeah, if price were king, these would be in the royal family.
     

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