If the motor splutters and produces excessive smoke when the throttle is nailed, the mixture is to rich. Wind the low end needle in around 15 degrees at a time. When the transition is sharp and very little smoke (if any) is produced, thats where you want the needle. On the other hand if there is no smoke produce when the throttle is nailed and the motor dies, the mixture is too lean. Then you just back the low end needle out the same way. If you stuff up and you have no idea where the needle is and the needle adjustments do nothing. Just close the throttle fully and wind the low end needle in until it stops, the back it out 1 1/2 turns and you should be back in the ball park. Do all adjustment with the engine stopped!!!! Once the transition is good you may need a small adjustment on the high end needle also. Hope this helps....