Question: What are the most wins in 1971 in 250cc class?
SQL: SELECT MAX("Wins") FROM "2-15161245-2" WHERE "Class" = '250cc' AND "Year" = 1971.0;

Question: What is the earliest year with less than 45 points for Yamaha team in 21st rank?
SQL: SELECT MIN("Year") FROM "2-15161245-2" WHERE "Points" < 45.0 AND "Team" = 'Yamaha' AND "Rank" = '21st';