The dirt bike engine number is an 11 digit identifier usually located on the right side of the engine case near the kickstarter (or where the kickstarter used to be if the bike has e-start).A separate form is required to obtain a surrogate VIN for a motor vehicle in Western Australia. Owner/Builders can request a low volume Vehicle Identification Number VIN for a new trailer. Obtain a Vehicle Identification Number (VIN) for a new trailer.