A Foxley starter is my choice.
No battery's, just good old petrol power
and you can move it to the bike fast-useful if the bike is already in the 'next race' enclosure and you have a delay-you cant keep reving up and getting hotter and hotter forever ... and bikes are hard to bump nowadays (modern ones are impossible).
Mind you IMHO it was a sad day when they stopped bump starts
Nothing will ever compare to the silence on the grid , a few nervous coughs ,the pulling back on compression the tension ,the scuffing of leather the footfall and then the first to burst into song followed by the symphony of noise and the climbing on with the foot just swinging over the seat and down just in time to collect second gear.
Hey Ho