Hi, your problem may be the primer base plate valves (especially if it's a zama carburettor --- they seem prone to this) which unfortunately can't be serviced as it's a sealed assembly, the cause of the problem is if fuel/oil mix is left in the machine (manufacturers normally recommend running the engine out of fuel until it stalls so the fuel system is "dry") when it's stored for a long period the petrol evaporates leaving a sticky oil residue that "glues" the flap valves to their seating (the sticky oil residue will be present through the rest of the carb clogging the other valves, diaphragm needle, filter gauzes and mixture airways ), you can obtain a new primer bulb baseplate (about £15) and try cleaning the rest of the carb but it would probably be easier and most time/cost effective to obtain a new carburettor (as a genuine part about £45) as i've tried a few times to clean these types of carb (they are known as "pumper" carbs ) and not usually had much success --- hope this helps
mark13_2001, August 2016
