How to adjust air flow screw on a yamaha blaster

OMG = there is a youtube video on it. can you believe that?

if close to head, gas adj, if on air box(filter) side of carb then air mix screw is normal 1 1/2 turns from lightly seated should get started then adj from there

check for air leaks around the air filter and/or clean the carb

Check that the breather in the fuel cap is still working. The breather has a hose with a one way valve.
You should be able to blow air in but not out. I hope that you are moving during that 1/2 hour as these motors require air flow for cooling.

Start at 1.5 turns out from fully closed.

the crankcase is filled with fuel from a leaking carburetor float (would be LOTSSSSS of smoke) OR Bad crankcase seal and its sucking in air, bad reed cage area seal, exhaust plugged up!

sounds like your mixture was leaned out because ur filter was cloged up ...making it run rich so was adjusted by screwing air screw out, now uv cleaned it, adjust it to make mixture richer by screwing back in until runs smotherly

a lot of people that take these apart put them back together backwards. make sure it is right. most of those carbs are not adjustable other than the jet itself. make sure your fuel tank is clean and fuel lines are clear/ fuel filters are clear or new.

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I would check the plastic heat isolator between the carb and cylinder head for leak.