yimcyco

I 'd check my valve clearance if the carbs are okay and you clean out the pilot circuit and turn the fuel screw out 3 turns after seated then compression spit back throu carbs is stalling it out also what is your idle set at sse between 1200 and 1500 rpm

most atv go through excessive heat cycle and lack of frequent oil changes elivates engine heat due excessivecarbon in motor this will cause stator assembly and magnetos to prematurely fail I'd check the stator or pick up output first

i would first check oil level you need to run quad for a 3 minutes and let sit for 2 minutes before checking stick excsessive on off throttle use can cause fuel to run through rings and elevating level if so replace oil

your sympton points to a float valve problem check to for excessive play with pin and pin holder if okay moose make a rebiuild kit for it you also may be experiencingspin back though the intake so check your valve clearance with that much fuel in air box i would change my oil due to fuel contamination spark plugs may also be foul due to excess fuel

sound like a safety switch try to engage brakes and shift into gear some atv has an engagment safety switch to keep accident from happening