390 SPITTING AND BACK FIRE ON START UP

AS I MENTIONED ON A PREVIOUSE POST PULLED HER FROM GARAGE AND STARTED THEN WOULDNT START AGAIN EVEN BROKE KICK START RETURN SPRING,SO BACK TOGETHER KNOW AND THIRD KICK BANG OFF SHE WHENT YIPEEE, BUT YET AGAIN SHE STALLED AND WOULDNT FIRE ? TRIED AGAIN AND , GETTING SOME SPITTING AND BACK FIRE WICH I NEVER HAD BEFORE. I GOT HERE RUNNING PRETTY SWEET LAST YEAR DAMMM

Pilot plugged? Even some gooey pre-mix will effect it. Gas usually evaps and leaves mix oil in carb if it wasn't drained.

Check for a broken flywheel woodruff key, flywheel could have slipped.

yep that was my next step i have drained fuel from tank to try some fresh and was going to strip carb and give it a good clean.will keep you informed

Had both those on the 78 390WR. When I bought it, it would start .... eventually ! Backfiring as it tried. Cleaned the carb out and that was solved.
Would not rev out. That was the woodruff key broken. As luck would have it, the flywheel had spun that hard it friction welded itself back to the crank 1mm from where it should have been. It was at that point I decided to rebuild the motor. That was 8 years ago, it's still sweet now. Not that it gets used much.

changed fuel stripped carb cleaned pilot got her running,but hesitant in low down ie pulling away in first and second,wouldnt idle either,stalled and wouldnt start again so put her back in the shed untill have little more time,strange because was running great last year.