11-03-19, 07:51 PM
If it's back firing it must be getting some bit of spark. Maybe rain water has got in your tank from a blocked drain at the filler neck or the drain pipe in the tank could be rusted out and the water is getting in the tank and it's in the carbs now so the bike can't start. You could try draining the carbs bowls and see if it starts after that. Also open the tank carefully have a look in around the filler cap and in the bottom of the tank for water.