when you haven`t got a choice (pushstart ?) ,what to do ?
A car`s battery has got a far bigger capacity (Amperehours AH) .
So it`s not the best idea when the starting procedure takes too long cause then It is possible that you burn some fuses the wiring .
With modern bikes you might face probs with electronic equipment (fuel-injection, on-board computer)
A RESET (don`t we know this one all...no joke) might occur, the anti theft device might go off and every biker in that parkinglot is jumping you....
Kidding, however anything electronical is quite sensitive to overcharge .
I even heard that car companies are advising against pushstarting a (modern) car cause the sudden charge combined with some missing parameters (enginespeed blabla) could destroy some equipment.