He said his wrist had given little trouble on a rough track he described as "brutal".
"It's going to niggle for a while yet but I can ride through it. It's not a problem."
Phillips is another rider revelling in the new challenge of a switch to MX1 bikes. He won two of the five races but needed to make a comeback through the field in race four.
National champion and defending Summercross title holder Cody Cooper (Papamoa) scored two race wins and finished third as he continued his comeback from knee surgery in May.
"I made some mistakes which made it hard for me but I can only blame myself," said Cooper.
"But I improved all day and in the last race I had a good start at last and got a convincing win."
Completing a successful day for the Phillips brothers was Michael Phillips who claimed the MX2 (250cc) honours.
A few weeks ago he would have been a Summercross spectator supporting his younger brother.
Then Phillips accepted a Honda Shop Racing offer to stand-in for injured Tauranga rider Aaron Wiltshier.
Against a classy MX2 field Phillips headed off Hamilton's Josiah Natzke (KTM) to take the title by a seven-point margin.
The other MX2 winner was national champ Kayne Lamont (Mangakino) but a spill in the fourth moto saw him helicoptered to hospital with suspected chest and shoulder injuries.
Winning the opening moto put Taupo's Wyatt Chase (Yamaha) in front of the three-race Youth MX (15-21 years) class. He followed up with a second and third while Ngatea's Benjamin Broad set the pace with two wins. Te Puke's Tyler Steiner (KTM) completed the Youth MX podium.
In a record Women's MX field of 36-riders, Auckland's Nikki Scott edged out Tauranga's Jessie Waterhouse (Yamaha) by five points to take the title.
Carter's victorious comeback Honda Summercross 2014 results:
MX1 (450cc): 1 Rhys Carter (Mt Maunganui) Suzuki, 246pts; 2 John Phillips (Rotorua) Honda, 244pts. 3 Cody Cooper (Papamoa) Honda, 240pts; 4 Ethan Martens (Auckland) Yamaha, 216pts; 5 Scott Columb (Queenstown) Yamaha, 208pts.
MX2 (250cc): 1 Michael Phillips (Rotorua) Honda, 244pts; 2 Josiah Natzke (Hamilton) KTM, 237pts; 3 Cam Dillon (Taupo) Honda, 229pts; 4 Scotty Canham (Rotorua) Kawasaki, 217pts; 5 Logan Blackburn (Te Puke) Suzuki, 208pts.
Youth MX (125cc and 250cc): 1 Wyatt Chase (Taupo) Yamaha, 151pts; 2 Benjamin Broad (Ngatea) Yamaha, 147pts; 3 Tyler Steiner (Te Puke) KTM, 137pts.
Women's MX: 1 Nikki Scott (Auckland) 160pts; 2 Jessie Waterhouse (Tauranga) Yamaha 155pts; 3 Julie Greenslade (Auckland) Kawasaki, 132pts.
Veterans MX (35-44 years): 1 Daniel Scrimgeour (Taupo) Yamaha, 165pts; 2 Larry Blair (Inglewood) KTM, 139pts; 3 Jonny Edwards (Gisborne) Honda, 130pts.
Veterans MX (45+ years): 1 Mitch Rowe (New Plymouth) KTM, 165pts; 2 Bevan Weal (Taupo) Yamaha, 146pts; 3 Geoffrey Hall (Taupo) Yamaha, 139pts.