I have a older , used Surpass 91 which is giving me grief. When the idle screw is set as per start point ( 2 1/2 - 3 turns ) motor won't run. The only setting which works is , idle screw 5 turns and high speed needle 1 turn . It is very rich BUT goes high to low without hesitation . It will also SOMETIMES stop suddenly ( at 3/4 to full rpm ) . When I open carb , fuel runs out > even with idle screw turn in to 1 1/2 turns. Tank is set as per req. 1/4" above center of barrel . The same settings are req. sitting upright on my test stand or inverted in my plane . ( although fuel seems to run out of carb more inverted) The clearence on valves is set correct and compression feels good .The high speed needle has a SLIGHT bend but seems to settle in concentric to axis once its screwed in 1/2 to 3/4 of the way. Can anyone diagnose these symptoms ?
Thanks in advance .