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Wild Piggy
08-09-2018, 05:07 PM
We just did a big bore upgrade to 80cc on a Mad Dog scooter. We changed carbs 5 times, new CDI, coil, stator, spark plug twice, even changed the head again. Starts and runs fine, until you take off, then it starts to spit and sputter. We pulled the engine out and replaced it with a brand new 49cc out of the box. Ran great, NO spit and sputtering. Any suggestion would be greatly appreciated.

JerryHawk250
08-09-2018, 05:12 PM
We will need a little more information. What size carb and what size jets? are you using the same carb and jets from the 49cc on the 80cc? BTW welcome to the forum.

Gh426
08-09-2018, 06:46 PM
are your cases sealed? vacuum leak??