Alabaster was last off the start line on Sunday after his bike failed to fire.
However he came out of the first lap in front and continued to extend his lead through to the finish over the 15km course.
The junior classes raced in the morning over a 12km course. It was a "shotgun" start with each class being set off at one minute intervals and racing for 90 minutes.
In the 125/250cc class Max Hefferen (Sanson) held a good lead after the first lap and went on to take the win for the round and the series title over Wanganui's Joe Wainhouse.
Points gathered during the two round series will be added to during four more motocross events planned for May, June, July and August to determine the Wanganui Dirt Bike Rider of the Year.
Results
Overall Junior Series: 13-16yrs (125/250cc): 1st - Max Hefferen 2nd - Joe Wainhouse, 3rd - Ollie Dennison.
8-12 years (85/150cc): 1st - Toby Winiata, 2nd - Riki Wainhouse, 3rd - Trent Culley.
13-16 years (85/150cc): 1st - Leroy Gwynn, 2nd - Blake Rountree, 3rd - Mitchell Loveridge.
Senior A Grade (over 250cc) class - Round 2: Charles Alabaster.
Overall Senior Series: A Grade (under 250cc): 1st - Ethan Brewer, 2nd - Danny Willemsen, 3rd - Matt Walker.
A Grade (over 250cc): 1st - Mark Dermer, 2nd - Duane Strachan, 3rd - Gareth Lewis.
Vets (30-39 years): 1st - Shamus Manson, 2nd - Roger Bland, 3rd - Jason Wakeling.
Vets (40+): 1st - Ant Rountree, 2nd - Shayne Wainhouse, 3rd - Pete Duxfield.
B Grade: 1st - Dean Christmas, 2nd - Gareth Lane, 3rd - Daniel Jervis.
Women: 1st - Courtney Alabaster, 2nd - Nicole Marshall, 3rd - Letitia Alabaster.
Overall Mini Series (up to 12): Intro Trail: 1st - Chase Williamson, 2nd - Ryan Matthews, 3rd - Caleb Houlihan. Mini Trail: 1st - Layton Mallinder, 2nd - Troy Bullock, 3rd - Hamish Harcus.
MX 65cc: 1st - Troy England, 2nd - Jet Ashworth, 3rd - Ajah Sullivan.