Suzuki 3 cylinder 50cc - yes you read that right - crazy stuff - all in all a good paper too as it charts this development https://www.grandprixengines.co.uk/Grand_Prix_Motorcycle_Engine_Development.pdf
[Suzuki even built in 1967 an experimental 3-cylinder 50cc with Stroke = 26.5mm which gave the still record value of 404HP/Litre.] Pretty impressive if that figure per litre could be maintained into larger cc engine.
Some good reading in there - I didn't want to spoil the surprise - that's 3 little pistons ~28mm diameter and I can imagine the sky high redline - amazing that they went as far as 14 speed gearboxes also, which obviously would have been necessary for tiny little engines with even narrower power bands 1967. The FIM limits on cylinders and gears for 1970 onward In mid-1967 there was a report from Japan (ref. 17) that Honda intended to return to all classes in 1968 with more cylinders:-a 3-cylinder 50, a 6-cylinder 125, a V8-cylinder 250 and a 6-cylinder 500. Alarmed by this and with an intention to reduce costs the FIM announced that in 1970 the number of cylinders permitted per class would be limited and all would be allowed only 6 gears ( the 1967 50cc Suzuki 2-stroke twin had got up to 14!).The figures were:-50cc class, one cylinder; 125 and 250cc, two; 350 and 500cc, four.
