If it's a 2 stroke and has good spark, another option could be a clogged muffler or muffler screen. Some models meant for use in California put a fine mesh screen between the exhaust port and the muffler. These screens clog quickly and are all but impossible to clean short of overnight soaking in Chemtool carb cleaner. Also 2 stroke mufflers do clog and are difficult to clean. Good luck
Larry McNeill fixit@texoma.net, March 2007