The Northeast Cambodia loop takes us from Phnom Penh to Kampong Cham, followed by Kratie, Stung Treng, Ban Lung (Ratanakiri), Sen Monorom (Mondulkiri) and Prey Veng before bringing us back to Phnom Penh. It is best to plan at least seven days for the trip. In order to ride at a reasonable pace with adequate time for sightseeing, I would suggest planning ten days for the loop. Personally, I spent nine days for the trip, with the last 2 days in Phnom Penh. The total distance I traveled was around 1500km.
Map of Cambodia and route taken