Unwanted All Black fullback Israel Dagg put the Magpies ahead 18-5 with his 28th minute try which West converted. Jackson sought the assistance of TMO Bruce Dockary before awarding Harbour second five-eighth Michael Little his 27th minute try.
Halangahu slotted the conversion.
It was a sloppy second quarter from the Magpies and Halangahu had the final say in the first half with a 40th minute penalty to keep his side in the hunt at 20-15.
Buckman's 42nd minute try came from a clever cross kick from West who landed the conversion to maintain his 100 per cent success rate.
O'Connor matched Buckman's feat with his 51st minute try off a clever short pass from lock Mark Abbott. West added the extras.
Three minutes later hooker Ash Dixon scored and West was again on target to have the Magpies ahead 41-15.
Harbour had a sniff when substitute forward Jordan Manihera scored in the 56th minute.
A converted penalty try had the challengers trailing 41-27 with four minutes remaining.
The Magpies had the final say when substitute halfback Chris Eaton scored off a Tongia intercept and West ended his player-of-the-match performance with his eighth success at goal from as many attempts.
Scorers:
Hawke's Bay 48 (Ryan Tongia, Israel Dagg, Richard Buckman, Brendon O'Connor, Ash Dixon, Chris Eaton tries; Ihaia West 6 cons, 2 pens), North Harbour 27 (Tevita Li, Michael Little tries; Daniel Halangahu ). HT: 20-15.