SCHEMA:
CREATE TABLE table_name_84 (wins INTEGER, points VARCHAR, year VARCHAR, class VARCHAR, team VARCHAR)
USER:
What is the average wins in 250cc class for Bultaco with 8 points later than 1966?

QUERY:
SELECT AVG(wins) FROM table_name_84 WHERE class = "250cc" AND team = "bultaco" AND year > 1966 AND points = 8