Nothing really.
Stock 1.4GL Twin Keihen Carbs, 90bhp
very good considering its 1989 with 180,000 miles on clock.
I use semi-synthetic oil, just had timing belt replaced and timing checked, runs on unleaded "normal" octane, no mods, is reasonably quick once 3500 revs is maintained and higher, read other comments and most are true on unmodded car.
Best of all is the engine does like being revved now and again over 5000 but max power is about 6400, I like it for what it is, don't thrash it too much cos I want it to last.
The best car of Honda.