That’s a 72 cc Yamaha G7s bottom end .. not a fs1 … I’ve used that bottom end with a 79 yam YZ 80 cylinder and head .. 30mm carb there’s video of that bike doing 85mph
On you tube
(80mph fizzy the banned ones part 2)
Part one was with the stock G7 top end stage 3 porting and spanny and 20mm card 80mph was videoed but must slower to top speed ..
that top end water cooled is what cc