Tried spraying WD40 down carburetter barrels, nothing happens, could indicate faulty ignition electrics, could not. Pulled out ignition coil and tested resistances on primary and secondary windings, appears to be good, gives a large ratio of the in/out voltages. Cleaned case and contacts while it was out. Put back in, no difference to start up. Tested spark plugs, there are sparks at each plug.