Parmakit 130 primavera

when i first start scooter from cold the engine fires upfine.i close the choke on the carb and keep the engine alive with small whips on the throttle,ok.but as soon as i put the scooter into first gear the engine stalls everytime with no revs.???then i restart the scoot no problem,but the scooter smokes like a trooper for a while..theres also a flat spot in first gear until it clears with a bit more throttle.ive had the carb out to clean ,ive changed the main jet twice from a 118 to 122 ,now on a 125.3rd and 4 th gear is mind is boggled ,any help would be grateful,cheers