There may be some kind of debris in the air fins - maybe the governors are stuck and it is reving too high and overheating. Or it may be low in oil.
The maximum speed of the 1961 Fiat 1100 4cyl 55hp is 75 MPH.
The maximum speed of a 1962 Renault gordini 1093 4cyl 55HP was 65mph or 104.60kph.
The maximum speed of a Peugeot 204 wagon 4cyl 55HP 1972 is 81 miles per hour.
50:1
90mph
The 805cc v-twin Suzuki has 52-55hp.
This is a 2 cycle engine.
845 cc / 51.6 cu in
73 mph.
Mine is 100:1, however best ring the dealership to make sure,
50:1 is usual, 32:1 is also OK according to some.
55hp @6500 rpm is the power of the Ctroen gsa 1979 engine and its maximum speed is 98 mph.