Stavros Nizamoglou replied to crazynuts's topic in Husqvarna 4 StrokeHello everyone.! Had the same problem on my 610, try and check the airbox first... The problem that you refer sometimes is so simple as some water drops inside the airbox after heavy rain or jet wash, that cause all the back firing and trouble starting. Solution 1 undo the airfilter and blow air until everything is completly dry.(if doesn't work)sol.2 Solution 2 undo the spark plug poor some gasoline and with gear move back and forward until the chamber is clean and dry put back the spark plug and try again. Hope i help before you check all the costly solutions..!