[mrgz250]

1st used a ngk dr9ea plug the air screw should be set about between 3 to 4 turns
if the bike has been sitting long & lots of miles on it take the carb off ck if the o ring is on the front of the manafold by the head its probley rotted out now u can take the carb apart & ck all the passages & clean it well use oem suzuki parts only mine is set at 4.5 turns
I get 85 to 100 mpg