Table schema:
CREATE TABLE table_name_90 (wins VARCHAR, year VARCHAR, class VARCHAR, points VARCHAR, team VARCHAR)

Question: How many wins for bikes with under 54 points, team yamaha, a 250cc bike, and before 1977?
SQL: SELECT COUNT(wins) FROM table_name_90 WHERE points < 54 AND team = "yamaha" AND class = "250cc" AND year < 1977