According to "Honda City Turbo II" page in the Honda Auto Archive and Auto Katalog 1985, p 232. World Class Cars #2: Honda (p 121) lists compression as 7,4:1.
Kurki-Suonio, Hannu (1985-03-19). "Autotieto 1985" [Car specifications 1985]. Tekniikan Maailma (in Finnish). Vol. 41, no. 5/85. Helsinki: TM-Julkaisu. p. Automaailma 28. ISSN0355-4287.