Table:
text: Chas Mortimer
Grand Prix motorcycle racing results
Grand Prix motorcycle racing results
Year_ Class_ Team Points Wins
1969 125cc Villa 5 0
1969 250cc Yamaha 8 0
1970 125cc Villa 5 0
1970 250cc Yamaha 30 0
1970 350cc Yamaha 15 0
1971 125cc Yamaha 48 1
1971 250cc Yamaha 42 0
1972 125cc Yamaha 87 1
1972 250cc Yamaha 18 0
1972 350cc Yamaha 0 0
1972 500cc Yamaha 42 1
1973 125cc Yamaha 75 1
1973 250cc Yamaha 40 0
1973 500cc Yamaha 8 0
1974 250cc Yamaha 41 1
1974 350cc Yamaha 29 0
1974 500cc Yamaha 4 0
1975 250cc Yamaha 46 1
1975 350cc Yamaha 31 0
1975 500cc Yamaha 23 0

text: Chas Mortimer
Grand Prix motorcycle racing results
Grand Prix motorcycle racing results
Year_ Class_ Team Points Wins
1976 250cc Yamaha 31 0
1976 350cc Yamaha 54 1
1976 500cc Yamaha 16 0
1977 250cc Yamaha 5 0
1977 350cc Yamaha 1 0
1978 250cc Yamaha 12 0
1979 250cc Yamaha 14 0
1984 250cc Yamaha 0 0

Question: Under Chas Mortimer how many wins for bikes under 54 points, Team Yamaha, a 250cc bike and pre 1977?