Monster Scooter Parts has the correct 82 link #428 chain for the Baja 90 (BA90) ATV. Please note that this chain contains 41 inner links and 41 outer links for a total of 82 links. This chain is sometimes referred to as having 41 links when counting only the outside links.
This is a size 428 chain with 1/2" pitch, 0.335" roller diameter, and 5/16" roller width.