Horouta reached 143-7 in 20 overs of a gutsy chase and owed much to the middle-order steel of Tony Bucheler (39, batting at six) and George Judd (unbeaten 31 from No 8).
Adams took 3-17 and Ashley McMillan 2-35.
Both have in recent weeks made a successful comeback to cricket for HSOB.
A man who has gone from strength to strength since returning to the game, E.J. Nepe, set the tone with the bat in Pioneer Ngātapa Green Caps’ eight wicket-win over Gisborne Boys’ High School Second XI (GBHS).
Wicketkeeper Nepe made 30 runs and shared in an opening stand of 93 with Tim Fox, who carried his bat for 58 in pursuit of 124 for victory.
Fox’s innings featured fine shots on both sides of the wicket and was the highest individual score in the competition on Saturday.
Boys’ High, under captain Kobe Donnelly, continued to show improvement with the bat in posting their highest T20 total to date of 123-4.
Powerhouse Matt Langford hit two sixes and four boundaries in his 26-ball knock of 45 at No 4.
Promising left-hander Bihandu Withanage made 29 at first drop.
Medium-pacer Zach Kirkpatrick (1-7 off two overs) and off-spinner Archie Gillies (1-17-4) were the pick of the Caps’ bowlers.
Finnbar Whitfield was GBHS’ sole wicket-taker with 2-22 in three overs of probing inswing.
Ngātapa lead the points standings on 20, HSOB have 16, GBHS 4 and Horouta 0.
Round 6 of the Doleman Cup 40-overs Premier Grade is on Saturday from 12 noon. HSOB play Coastal Concrete OBR on HBR 1 and Moshim’s Spice Horouta play GBHS First XI on the rep wicket.
The final is the following Saturday.
In Round 6 of the Reserve Grade T20 from 2pm, GBHS Second XI face Horouta on HBR 2, while HSOB Presidents take on Ngātapa on HBR 4 in a dress rehearsal for the final on December 13.