I just got a 1991 G-9 gas Yamaha and got it running but as long as the air filter is on i need to pull the choke to keep up power it starts fine now but when running i need to pull choke, it seems to have plenty of power. I have cleaned the plug, air filter, carb and tightened the carb mounting bolts. i havent set the air mixter screw as i have two threads with different adjustments, one is out 1.25 turns and the other is out 2.5 tirns. any suggestions as this is my first cart?