Wont stay running..

[TPapp]

The 86' Elite 80 I just purchased will not stay running unless I am continuously spraying starter fluid into it. I completely took apart the carb and cleaned every part, replaced the fuel lines and filter and gas is pumping through them, cleaned the air filter, it gets a spark and put new gas in it yet it still wont run. Adjusting the screws doesn't help either. The spark plug is black but I haven't gotten a new one because it sparks. What could I have possibly missed that is keeping it from running?

[Keoni]

Just change the spark plug regardless if it is still sparking, spark can be weak and still seem like it is a good enough spark. Normally if it runs with starter fluid but doesn't without it I would assume that the cylinder isn't getting gas but lets assume it is, I'd check the valves to see if they are within tolerences and if not have them adjusted cause it does make a big difference on those 4 stroke motors but also keep in mind I'm not a 4 stroke mechanic