Jamie Hamilton and William Dunlop ruled out of Southern 100

Jamie Hamilton leads William Dunlop at Skerries

Northern Ireland riders William Dunlop and Jamie Hamilton will not be on the grid for this week's Southern 100 road races on the Isle of Man.

Dunlop believes he is not yet fit enough to do himself justice on the physically demanding Billown circuit.

The 28-year-old has made a swift recovery from a leg fracture and hopes to race at Walderstown this weekend.

Hamilton faces a spell on the sidelines after breaking his pelvis and suffering a dislocated shoulder at Skerries.

The 23-year-old from Ballyclare also cracked his sternum and sustained a broken rib and bruising to his lungs after crashing out during the Grand Final on Saturday.

The Wilson Craig Honda rider came off at the chicane on the final lap of the feature Superbike race while battling for the lead with eventual winner and circuit newcomer Dan Kneen.

Hamilton had followed up his four-timer at the Bush road races the previous week by winning the Open and Supertwins classes at the Skerries meeting.

He must now be rated an unlikely starter for the Ulster Grand Prix at Dundrod next month and will definitely miss the Armoy road races on 25 and 26 July.

Dunlop won the 600cc race at Skerries but has opted to sit out the Southern 100 as he continues his return to full fitness following a crash during the Senior TT in June.

Michael Dunlop, Guy Martin, Dean Harrison, Kneen and Conor Cummins head the entry list for this week's event at Castletown.