My good friend has a 1996 KX250. It was running great last weekend. This weekend, it won't stay running. Changed the plug and checked the spark. If we lay the pulg on top of the head the spark is VERY weak. If we hold it off the head about 1/4 inch, spark is VERY good. :coocoo: It will fire off but stall almost immediately when you give it gas. Carb is clean and so is the air filter. Any ideas before we start throwing parts at this thing??? Thanks.