Police arrested 101 motorcyclists on Friday night after their motorcycles were found to have been illegally modified for road racing.
In a weekly crackdown on road racing, police from the Metropolitan Police Division 7 set up checkpoints on roads in the division's jurisdiction and made the arrests.
Traffic police chief Pol Maj Gen Nithithorn Jintakanon told a press conference at the Metropolitan Police Division 7, that 63 of the arrested were under 18.
He said police also seized 111 illegally modified motorcycles, and 16 of them were big-bike motorcycles.
He said police also checked 30 motorcycle repair shops in the division's area and seized four exhaust pipes that would emit noises louder than the legal limit of 96 dB.