have osfx.25 on sturdybirdy broke engine in with help of hobby shop guy engine runs great is hard to start dosent like comeing past 1.4 throtle till its run 2min. its real touchy dies restarts dies restarts then it starts and runs good tunes good do pich fuel line check for high and low settings and its good to go put her up she flew dead sticked got her down ok wants to restart but wont gave up for to day will probly run again but should i have to play around with it so much every time i want to run it how long to warm up engine are speratic air bubbles a problem seems to runn good sometimes and thier and sometimes it wont run good and their are bubbles in fuel line its been 35 to 45 deg out during its run life to day with first dead stick it was 45 deg what am i doing wrong help this is my first engine