Lightweight TT

The 1922 event was the first time the Lightweight TT race took place, won by a motorcycle-journalist Geoff S. Davison, riding a Levis at an average speed of 49.89 mph (80.29 km/h) for seven laps of the Snaefell Mountain Course. In the changes following the loss of FIM World Championship status after the 1976 event, the Lightweight TT event was dropped with the 250 cc machines running for the Junior TT in place of the now defunct 350 cc formula. The Lightweight TT returned in 1995 before being split into two distinct events from 1999, dropping from the schedule again after 2003. As with the Ultra-Lightweight TT Race, it was reintroduced 2008–2009 when held on the Billown short road circuit; and then dropped again from the race schedule on cost grounds.

• 1924–1948 For motorcycles not exceeding 250 cc engine capacity.
• 1949–1953 FIM World Championship event for motorcycles not exceeding 250 cc engine capacity, held on the Snaefell mountain course.
• 1954–1959 FIM World Championship event for motorcycles not exceeding 250 cc engine capacity, held on the Clypse Course.
• 1960–1976 FIM World Championship event for motorcycles not exceeding 250 cc engine capacity, held on the Mountain Course.
• 1977–1994 event not run (250 cc formula run as Junior TT).
• 1995–1998 for 2-stroke motorcycles not exceeding 250 cc engine capacity, and 4-stroke motorcycles not exceeding 400 cc, held on the Mountain Course.
• 1999–2003 Lightweight 400 TT for 4-stroke motorcycles not exceeding 400 cc engine capacity, held on the Mountain Course.
• 1999–2002 Lightweight 250 TT for 2-stroke motorcycles not exceeding 250 cc engine capacity, held on the Mountain Course (the category running within Junior TT in 2003).
• 2008–2009 for motorcycles not exceeding 250 cc engine capacity, held on the Billown Circuit.
• 2012– The event was re-introduced from the 2012 event for water-cooled four-stroke twin cylinder not exceeding an engine capacity of 650 cc and complying with the ACU Standing Regulations.

The 2019 specifications for entries into the Lightweight TT race are:

• Machines must comply with general technical rules as per ACU Standing Regulations and 2019 Isle of Man TT race regulations.
  • Any four-stroke twin cylinder motorcycle originally sold for road use with a water-cooled engine of up to 650 cc engine capacity.
  • Eligible machines must be from models homologated for UK road use 2009 or later.

Mininium weight for the Lightweight TT class is 161 kilograms (355 lb).