check fuel flow at fuel line let it run into a container if it is slow a blocked fuel filter on top of the fuel tap could be the problem, if it runs out good then slows it is probably the vent in the fuel cap,if all good then take the end cap which holds the needle valve and float off the carburator to do this unscrew the main jet which is the brass screw and check for debris in the jet clean out if blocked compressed air is good the debris gets in usually due to amissing fuel filter they get knocked off the top of the tap,when fitting the end cap back on make sure the needle valve is fitted the right way pointy end to the seat and the o-ring is in good nick and positioned correctly .Hold upside down and look across face of float it should be just about even with end cap, if sticking out (end cap distorted renew end cap) float level usually even with the radius of bottom of float and end cap or top of float and line on end cap, refit and see if it goes. No luck involved it is caused by something, has got a vaccume govenor hose from bottom of block to rear of carburator make sure is connected will over-revv if off make sure hose from rear of carb holds vaccume if not then diaphram in back is leaking .All of this over revving or leaning out can cause over-heating of the engine and piston damage ,take the muffler off and have a look down the exhaust port, scoring on the piston if evident will lower compression wont run for long.Always be carefull when working with petrol and lawnmowers
Dave Fix, May 2011
