Kettering rider John McBride is in hospital with major fractures after a high speed crash at Gorse Lea in the final minutes of last night's first timed practice.
Guy Martin (pictured) topped the Superbikes, ahead of John McGuinness and a rejuvenated Adrian Archibald.
Martin's average lap speed of 126.02mph left him just ahead of McGuinness (125.96) and Archibald (125.86), with Cameron Donald (125.82), Bruce Anstey (125.77) and Ryan Farquhar (125.35) close behind.
Ian Hutchinson had a problem when his R6 Yamaha caught fire in the holding area before the session had even begun.
The Bingley rider was clearly unsettled, he eventually went out but was again out of luck, pulling off the course at the Cronk y Voddy and making his way back to the Grandstand.
With good conditions, the riders were keen to get in as many laps as possible on all their machines and McGuinness set the fastest Supersport lap of the evening at 122.30mph ahead of Cummins (121.49), Hutchinson (120.36) and Stewart (119.95).
In the Superstock class Anstey recorded a speed of 125.94mph, faster than his earlier Superbike time, with Guy Martin second (124.08) and Cameron Donald third (123.29).
As well as the McBride incident, Angelo Conti was described as having a leg injury after an incident at the 33rd.
The F2 sidesars lost half of their session while debris was cleared following McBride's accident.
Nick Crowe and Mark Cox set the pace at 112.85mph on their LCR Honda whilst the Suzuki powered outfit of John Holden and Andy Winkle wasn't too far behind at 111mph.
Tim Reeves and Patrick Farrance showed their world championship class with a lap of 103.71mph.
Dave Molyneux and Dan Sayle encountered a few problems and could only post a lap of 107.52mph.
The Mountain Road closes at 5pm, the rest of the circuit at 6pm for a further practice session this evening.