I have a 6 HP diesel air cooled Yanmar generator with a pull start. Yes, you have to pull hard, but you pull ONCE. Never fails to start on ONE pull. Heavy bugger, not sure it is the best fit for a push or walk behind mower.
i use a 36" commercial hydro zero turn walk behind for my pond dams. although not a Kubota as OP asked for, but a heavy duty zero turn walk behind that perfectly solves the problem a conventional zero turn sit down mower cannot on slopes. but do recommend bar tires rather than std turf
plus it doesn't tear up the turf on slopes as a conventional zero turn often does. safer too