Grubee GT4

Discussion in '2-Stroke Engines' started by TomatCP, Nov 21, 2010.

  1. TomatCP

    TomatCP New Member

    Hi ive had a grubee GT4 engine which runs well but at full throttle it hits about 26-27 mph (bike speedo) and then acts as if it is running out of fuel. The result is my top speed pulses from around 25-26 which sounds good and the engine can maintain but above that it acts like its out of fuel. I thought it may be too small of a main jet so i bought bigger jets but the problem doesnt seem to be fixed and im running out of options. Anyone experience this/can you help?

  2. GearNut

    GearNut Active Member

    I bet it is running too rich. What color is the spark plug? Black= too rich, white= too lean.
    Chocolate brown to leather brown= perfect.