Bimodality is observed on the size of the heaviest released fragment for semi-peripheral heavy ion induced reactions in the intermediate energy domain. From lattice-gas calculations, this signal can sign a phase transition even if the system has not reached a complete equilibrium. It is shown from the data that it is correlated with other possible phase transition signals. The two bimodality solutions correspond to different excitation energies and to similar temperatures as expected if bimodality is due to a liquid-gas phase transition. ©2007 American Institute of Physics