Putting a motorcycle in a racing game is a whole diffrent story. The game allows custom addons to be installed, so there's no problem with using a motorcycle model, setting some game specs for it and there you go. Modding action sport games is whole lot diffrent though. In thps you can mess with the files and unlock some weird tricks, as well as download other kinds of mods, but Im afraid that any version of DMFBMX is sadly unmodable.