So yes as for the popping coming from the carb. The "backfire" means just that. What happens is just like what Terry is going thru. The combustion area becomes to wet, every so often the coil will fire which causes a misfire. How does it happen? Glad you asked
In this case and with this ignition system there are 2 reasons for it: The coils are not being triggered in sync with the engine timing. This is what we are looking for as to what the cause is. The next reality is this system is based on "wasted spark" that means a coil is triggered on every exhaust stroke as well!
I am going to briefly explain combustion, my hope is that you can visualize the single event that begins the combustion cycle: Each combustion has a duration (time) this is further explained through propagation (the progression of ignition to the fuel/air charge) This can be visualized by 1 single sheet of tissue crumpled up into a ball the lit at the top - as the flame spreads the tissue and flame change shape or propagate the time this takes is called "duration"!
The exspansion is the energy that drives the piston the crank and the valve train and that is continuations. So if the duration is to long then the backfire will light the next charge as it enters past the intake valve on the intake stroke causing the "backfire"!
Next you misinterpret my disadvantage comment. NO reason for you to know my background but enough to say I have worked thru many disadvantages turning them into advantages. I'll share this too: I have been working with a 38 year old that was hit by a train suffering many injuries including head trauma. He is visually not the man he use to be, he walks like a toy soldier, his beautiful loving girlfriend and mother asked me to help him. To be honest with all I didn't believe I could but I found a way and I now know he can, So I persist because he tries.
I have a small group of PTSD that I work with as well. Each one of us is different but none of us ever laugh at the other unless we all laugh together.
Oh and I also train good people to defend...... None of or any of the above is done for profit. I think I am qualified to know a bit about disadvantage to advantage