Stumped on why she won't run!

[IdiotBikeOwner]

One day several months ago, I was riding my pretty much brand new 80cc motorized bike and it started losing power. Soon, I had to pedal as hard as I could just to keep it running. I've tried so many things, so here is a list of what I've done, and what my symptoms are. Perhaps y'all can un-stump my mind. I'm pretty new to this whole thing so I'm sure it's just a simple thing I've done wrong or overlooked.

What I've done:
Replaced with brand new parts:
Spark plug
CDI
Carb
Fuel line and fuel filter
Head gasket
Exhaust Gasket (It disintegrated when I took off the exhaust pipe)

Symptoms:
Won't continue to run without constant, hard peddling
Drags/lurches
Backfires
White smoke constantly coming from exhaust, fuel leaking from exhaust
Won't Idle

Hit me with your ideas please! I'd love to get this puppy back on the road!

 

[HumanPerson]

down jet possibly?

 

[HumanPerson]

What # jet ya have in that nue carb?

 

[Wrench]

Welcome to the forum Idiot.

 

[Chainlube]

Check the float and float needle, after carb change debris can gets in and keep the needle from seating. Best to remove float and needle, and check the seat for dirt, the smallest piece of sediment in there can cause it to flood. You can also check your spark, even though I don't think it's spark, put the plug on the wire and rest it on top of the engine and roll the bike forward.

 

[Tyler6357]

Check to make sure the head is completely sealed, if you can get it started usually you can feel air shooting out from somewhere around the head gasket if it has an air leak. Torque the head nuts to about 15 foot pounds.

 

[intrepid]

Magneto goes bad a lot, check that and do a lot of youtube research. A way I broke my bike is I couldn't start it so I tried to heat it with a giant heat jet, frying the cdi cables in the process. The bike didn't end up starting, I ended up realizing I forgot to turn my fuel on the whole time and now had a real broken bike with a fried cdi. Make sure your fuel is on, since you mentioned overlooking simple details.