The excitation of pulse of transition radiation, which occurs when the bunch of charged particles is injected through the front metal wall into the semiinfinite cylindrical waveguide, is investigated. The exact formulas for the fields of thin ring-shaped bunch, which contain Lommel functions of two variables, are obtained. The energy efficiency, power and spectrum of radiation, excited by finite size charged bunch in vacuum waveguide, are determined with the help of numerical calculations. Multimode field excitation is considered. It is shown, that under certain conditions the excited electromagnetic pulse has short duration, high intensity and wide frequency spectrum. The influence of various parameters of waveguide and charged bunch (current, length and radius of bunch, waveguide radius, longitudinal coordinate of observation point) on the efficiency of transition pulse excitation is studied.