How old is this lawnmower? Yard machines, Briggs and Stratton engine YBSXS. 1581VA is what it says on the engine sticker, it's American, but was brought to the UK a long time ago :
briggs 17,5 le fűnyíró traktor motor | Kertmotor - kerti gépek, alkatrészek, stihl alkatrészek, utángyártott, DMT alaktrészek