Kennedy Owino netted a brace for KCB, with Simon Abuko and Michael Osundwa also getting their names on the scoresheet to help the bankers put behind a disappointing exit from the FKF Shield.
The win saw KCB take their points tally to 36, just two behind leaders Ushuru, who have amassed 38 points from 19 matches.
Nairobi City Stars came from behind to edge out FC Talanta 2-1 in the second match played at the same venue.
After a goalless first half, Anthony Gicho gave Talanta the lead from a corner kick. Returning David Agesa would, however, restore parity, with Joseph Kariuki netting the winner late in the match.
Four more matches will be played on Saturday, June 30, 2018, with the highlight being a top of the table clash pitting Ushuru against Western Stima. The match, as well as the one pitting Kangemi All-Stars against Nakuru All Stars, will be played at the Ruaraka Stadium.
Friday Results: KCB 4-0 Modern Coast Rangers, Nairobi City Stars 2-1 FC Talanta
Saturday Fixtures: St. Joseph’s Youth vs GFE 105 (Afraha Stadium, 1 pm), Kisumu All Stars vs Coast Stima (Moi Stadium Kisumu, 3 pm), Kangemi All-Stars vs Nakuru All-Stars (Ruaraka Grounds, 4.15 pm), Ushuru vs Western Stima (Ruaraka Grounds, 2 pm)
Sunday Fixtures: Green Commandos vs Nairobi Stima (Bukhungu Stadium, 3 pm), Kibera Black Stars vs Bidco United (Ruaraka Grounds, 3 pm), Isibania vs Administration Police (Awendo Green Stadium, 3 pm).