The A grade will now race with the B grade, mostly the 30-plus veterans with form, and the race will be over four laps, not five as originally planned.
Leading B grade hopefuls include Bevan Cheatley, Adrian Pettit, Phillip Groves and Pat Johnstone (Wanganui), Brent Bismark (Marton), Scott Ardern (Hamilton), and Denay Cottam (NP, winner of the Feilding to Apiti race last weekend).
NBational track representative Cassie Cameron is also in the race.
The C grade features riders like Jeremy Cottam (New Plymouth), likely favourite Paul Lundon (Wellington), and Wanganui's Brian Scrimshaw, Dan Richards, Alan Luff and Paul Forrest (Wanganui).
That race starts at 9.30am, over laps, with the under-17s at 9.40am and the under-15s at 9.50am, both over two laps of the small circuit.
Race director Maurice Mildenhall said the Grand Prix events would be staged around the Oceania circuit, from the start-finish at Brunswick hall. The course sees the riders travel in a 23km loop down Brunswick Rd, across to Kai Iwi and return via Goat Valley on State Highway 3 and Western Line.
The open field will race for the John Bull Cup and the $1000 prize purse is expected to appeal.