Carb has a H and L marking.
L for idle (low speed), H for high speed.
Note the position of the H jet and tweak it 1/4 of a turn either way and test.
Dont turn too far and dont forget your original position, if you run too lean its by by engine.
Sometimes the mixture screws are under a cover to stop people playing with then.
My Talon chainsaw had them under a red plastic oval cover that i had to pry off.
Before you do anything make sure your air cleaner is clean.
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