CREATE TABLE table_name_84 (wins INTEGER, points VARCHAR(255), year VARCHAR(255), class VARCHAR(255), team VARCHAR(255))
What is the average wins in 250cc class for Bultaco with 8 points later than 1966?
    
SQL: SELECT AVG(wins) FROM table_name_84 WHERE class = "250cc" AND team = "bultaco" AND year > 1966 AND points = 8