Yamaha FX-1 is a stand-up watercraft built in very limited numbers in 1994 & 1995. Around 1500 were made. It carried the same 701cc 61x single carb engine as the Super Jet and had a lighter and narrower hull.
Similar in size to those in the mid 1970s.
Factory specifications on the 1994 FX-1 vs Super Jet
(Taken from the 1994 Yamaha water craft catalog.)
144mm pump vs. 122mm pump
FX-1 and 1994-1995 Super Jet had identical 701cc carburetor engines with 63 hp.
References
Yamaha FX-1 Wikipedia(Text) CC BY-SA