Renault Billancourt engine
Different cylinder capacity

engine types
690
662-2 - 680
662-1
839
B1B - 670 - 800 - Ventoux1093
cylinder capacity
0.6 L (603 cc)
0.7 L (747 cc)
0.8 L (760 cc)
0.8 L (782 cc)
0.8 L (845 cc)
bore
49 mm (1.93 in)
54.5 mm (2.15 in)
55 mm (2.17 in)
55.8 mm (2.20 in)
58 mm (2.28 in)
stroke
80 mm (3.15 in)
80 mm (3.15 in)
80 mm (3.15 in)
80 mm (3.15 in)
80 mm (3.15 in)

Question: What were the sizes of the bore and stroke reduced to?
Answer: The size of the bore was reduced from 55 to 54.5 mm (2.17 to 2.15 in), while the stroke remained unchanged.