City dominated possession early and created a number of good chances, with Roy Hissey wasting an opportunity to take the lead after some impressive lead-up play by Papa Kpatar.
Kpatar�s early brilliance was a sign of what was to come, with the powerful wide player setting up City�s first four goals.
Firstly, a lovely through ball released teenaged striker Boyle, who lifted the ball over the onrushing keeper to take the lead; the second came soon after when another pass found Boyle again, and this time the striker skipped past his marker and fired low into the net.
Christian Hogge put the ball into an empty net following yet another Kpatar pass, and the fourth came following a surging solo run and shot, which cannoned off the cross bar but fell to Boyle who headed home to complete his hat-trick.
Cruising with a four-goal cushion, City showed no signs of letting up and before half-time they had added a fifth, and Boyle his fourth, courtesy of a neat turn and cross from Alex Grayson.
The second half started as the first had finished, and City registered their sixth goal after Ryan Kennedy�s corner found captain Sean Brady, who volleyed into the roof of the net from close range.
Kennedy got himself on the scoreboard soon after, the midfielder finding himself in space about 20 metres out, and his powerful shot left the Kelmscott keeper with no chance for a 7-0 lead.
The match started to resemble a training run for City as they passed the ball with little pressure and continued to build attacks with no resistance shown by Kelmscott�s deflated defence.
The eighth goal arrived when substitute David Clark linked up with Boyle, who set Clark up for a low finish past the keeper.
The rout was completed when substitute Gersholm Rowland ran on to a neat through ball and his sublime touch and turn took him past the keeper before he rolled the ball into an empty net for arguably the best goal of the nine.
City remain a point clear of Forrestfield United at the top of the State League Division 2 ladder, Forrestfield keeping the pressure on with a comfortable 4-0 win over Ellenbrook United.
They face a difficult away trip to mid-table Quinns FC tomorrow afternoon. When the two sides met in round five, City were 3-1 winners.
A disciplined and professional performance from the young Rockingham sides made it a clean sweep for the club in all divisions, with City�s reserves defeating Kelmscott 7-1 thanks to a hat-trick from Josh MacKinder, while the under 18s ran out 5-1 winners.