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Race 3; Lightweight Classic RaceWednesday 27 August 2008 – Mountain Course 3 laps – 113.00 miles
- Class B for motorcycles exceeding 175 cc and not exceeding 250 cc.
| Rank | Rider | Team | Speed | Time | | 1 |  Wednesday 27 August 2008 – Mountain Course 3 laps – 113.00 miles
- Two-stroke motorcycles exceeding 201 cc and not exceeding 250 cc.
- Four-stroke four-cylinder motorcycles exceeding 550 cc and not exceeding 600 cc.
- Four-stroke twin-cylinder motorcycles exceeding 651 cc and not exceeding 750 cc.
| Rank | Rider | Team | Speed | Time | | 1 | 
Race 5; Senior Manx Grand PrixSaturday 30 August 2008 – Mountain Course 2 laps – 75.46 miles – Reduced Race Distance.
- Four-stroke Four-cylinder motorcycles exceeding 550 cc and not exceeding 750 cc.
- Four-stroke Twin-cylinder motorcycles exceeding 651 cc and not exceeding 1000 cc.
- Four-stroke Three-cylinder motorcycles exceeding 601 cc and not exceeding 675 cc.
| Rank | Rider | Team | Speed | Time | | 1 | 
Race 6a; Lightweight Manx Grand PrixSaturday 30 August 2008 – Mountain Course 3 laps – 113.00 miles – Reduced Race Distance.
- Two-stroke motorcycles 201 cc – 350 cc
| Rank | Rider | Team | Speed | Time | | 1 | 
Race 6b; Ultra-Lightweight Manx Grand PrixSaturday 30 August 2008 – Mountain Course 3 laps – 113.00 miles – Reduced Race Distance.
- Two-stroke motorcycles up to 125 cc, 6 gears maximum.
- Four-stroke motorcycles 251 cc – 401 cc
- Up to 650 cc Four-stroke twin-cylinder.
| Rank | Rider | Team | Speed | Time | | 1 | 
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