Sometimes it is necessary to push start a sportbike especially when they are hot. The engines have very tight tolerances and the mechanical load is just too much for the smaller batteries. It is best to do a push start in second gear as the load in first gear will skid to a stop. Just not enough traction to turn the engine over. The procedure is to get the bike rolling as fast as you can, jump on, shift into second, pop the clutch while jumping down on the seat to apply more weight to the rear wheel for more traction. The following video shows a push start with a few buddies helping to push.
If you are lucky it will start. It helps to have extra friends around to help push but can be done by a solo rider. Just run beside the bike pushing until it is as fast as you can get it and then jump on and bump start. Usually it is a bad or lowly charged battery causing the need to push start the bike. Keep your battery in top shape and with luck you may never need to do a push start. As always, enjoy the ride!