Andy Fenton set the fastest time in the opening practice session of the Manx Grand Prix on Monday evening.
The Braddan racer, who made his mountain Course debut in 2010, posted a lap of 113.868mph to top the Junior Class and the overall leaderboard.
Paul Smyth (112.470) and Alan Jackson (111.407) were close behind in the Junior times.
Meanwhile, Tamworth racer, Peter Symes topped the Senior Class with a lap time of 111.197mph.
The 53 newcomers were first away from Glencrutchery Road on a speed controlled, untimed lap in groups of six under the guidance of experienced TT and MGP competitors, including last year's Senior MGP winner Si Fulton.
Conditions were described as good with dry roads all round the Mountain Course but competitors were warned about bright sunlight and strobe effects through the trees.
The Classic, Post Classic and Lightweight Class went out in the second group with TT star Ryan Farquhar setting the second fastest time of the night on his 1983 Suzuki F1 113.516mph.
Joe Phillips posted the fastest time in the Supertwins class (109.313) while Alistair Haworth (104.994) was the quickest Lightweight class rider.
The newcomers went out at the back of the final group with William Davison, Karl Foster, Stuart Hall and David Kennington all posting 100mph laps.
The second practice will get under way at 18:20BST on Tuesday.