Ten minutes after mowing this afternoon, the C-125 spluttered to a stop and refused to restart. Pushed it back to the workshop and after getting my breath back, investigated. Plug sparking ok but dry. Was going to check the points but as I knelt to remove the cover, I noticed petrol leaking from the air filter.
Reached up and turned the ignition key. Engine turned over and petrol flowed out of the carb. Removed the float bowl which was clean inside. Rattled the float up and down, while turning the key and fuel came out. Then gently held the float up and fuel stopped flowing.
Put the bowl back and tried starting again. Engine fired up and no sign of fuel leaking out of carb. Finished 2hrs of mowing with out any more problems.
I reckon a speck of dirt had been stopping the float needle valve from seating properly.