Could be vapor lock (tank not properly vented). could be dirt in your carb, in which case you have to take apart your carb and pay attention to where every tiny piece goes, if you dont have an air compressor then wipe the jet and the fule valve best you can and blow air through with your mouth. the gas will make your lips tingle, but wont make you sick. if you have a cns carb, you could try to tune it, some have had success with this and others have not. best suggestion is to get an NT or old stock carb. If you have a cns, most likely thats the problem in itself. could also be the fuel line itself is clogged. blow air through it and see if anything comes out. after blowing air through the fuel line, attach it to the gas tank but not the carb and check the flow. if the flow isnt good, remove the line and check the flow again. if flow still isnt good, its probably vapor lock. REMOVE the cap and drill a small hole in the top. if you still have problems, its either something in the carb or the carb itself. you could also check the head bolts. loose head bolts can cause a loss of compression. check everything i listed and if you still have problems, replace your carburetor.
