What documents do I need to get a residency letter from immigration in Thailand for buying a second-hand bike?

To obtain a residency letter from immigration for purchasing a second-hand bike in Thailand, you will need the following documents: a residency letter request, a color copy of your condo ownership (chanuk), two photos, your passport, and potentially photocopies of all necessary documents. Additionally, having a 'yellow book' for your condo may negate the need for the residency letter. It's also advisable to carry your TM 30 forms, which include copies of your passport and the relevant stamps. For the motorcycle license, a rider medical assessment costing around 150 THB is required.