I agree it's a tunning issue....once you get the motor to start let it warm up.......go to high power and set the max by ear...you can use a tach if you like...once set to max leave it at max...don't richen....now go to low and set throttle to give about 2500RPM...now adjust the low end for max by ear with out touching the throttle.....shut it down and let cool. see if you start better......with a good transition...then check on the next flight