Kymco People 150 "Backfire"?

[dwarnimont]

My scooter has recently started to have a faint "backfire".  It's more like an almost backfire with a poof or subtle puff not ending the a real pop like cars.  I replaced the carb and it's the same.  What area of the engine should I be investigating?  Someone said the timing may be off. If this is a real thing, where can if find information to help me improve timing?
Thanks, Dave

[Ruffus]

@dwarnimont welcome here!
Give some more info why you changed the carb, some more data about your scoot, please.
-was your cylinderhead off?
-did you tap your valves correctely?

-this puffing COULD be caused by some false air entering between carb and cylinder head, means your manifold there is sucking in
-or either to lean or too rich fuel mix
-how does your sparkplug electrode look like after a short drive, greasy or white/ brownish
-guess you renewed your airfilter, sparkplug and cap?

Check all this and maybe give us a feedback.