Carby New HS142F drilling out the carb metering mix screw

Discussion in '2-Stroke Engines' started by darwin, May 2, 2014.

  1. darwin

    darwin Well-Known Member

    Anyone have any experience with this. There's 2 possible locations. This thing is a pig, gasbike brand new motor. Idles like a champ and has torque but no top end................I'm thinking it's new and needs to be ridden and all is well. But it sucks seems like 15mph top end and should be better. I'm not happy. 1-1/8th drive roller.
     

  2. KCvale

    KCvale Motorized Bicycle Vendor

    I have built several gasbaike 142F 4G combo MB's and never had to **** with drilling the carb,

    Altitude may be a factor, we are at 1100' here in phoenix and 2 1/2 turns out on the idle air works great and with the kit sprockets for the 20t/80T freewheel 10T solid drive sprocket they will hit near 30MPH out of the box on a 26" bike.

    [​IMG]

    I much prefer using them with a jackshaft like this

    [​IMG]

    But on a budget on a 29" wheel bike like a Macargi like this.

    [​IMG]

    Perhaps you some drag issues somewhere?
    Like brakes dragging, low tires, etc?
     
  3. darwin

    darwin Well-Known Member

    Isn't the valve specs on the hs142f, intake .003, ex .004? If they are then they're spot on. This thing is driving me nuts. Runs perfect, starts on 1/2 pulls when cold but no top end like it should. This thing should run 30 mph all day long, the torque is impressive............the carb mixture screw is covered up by the epa rules, with it running so good can't see the carb being the problem. I'm stumped.
     
  4. KCvale

    KCvale Motorized Bicycle Vendor

    Does your bike pedal with the engine off pretty easy?
     
  5. darwin

    darwin Well-Known Member

    The clutch bell and the FD bearings rolled good, I only let the FD channel rest on the tire and then maybe deflect the tire a 1/4 in. Checked the muffler for a restriction, nada.
     
  6. dougsr.874

    dougsr.874 Active Member

    The brass cover over the mixture screw can be drilled out....underneath you will find a regular adjustment screw....at least that's the way it was on the one I had.....but don't know if that will fix your problem..
     
  7. darwin

    darwin Well-Known Member

    Update, rode 15 miles yesterday and went by one of those radar signs that the police put on the sides of the road at times. It stated 21 mph pushing it and it felt improved over the last ride. Maybe it just needs broken in some more? If so this motor is tight like a virgin, never had a new motor act like this one. Unbelievable torque, a hill I used to need to pedal to climb with the Honda this sucker will climb all by its lonesome. Strange for a motor from gasbike with all the negs they get.
     
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