Kawasaki GPX 600R from 0 to 100 km/h 3,93 seconds

The old Kawasaki GPX 600R is capable to reach 100 km/h in only 3,93 seconds or below. Cycle World magazine in the 1987 Ninja 600R review reported 3,5 seconds from 0 to 60 mph with a top speed of 141 mph. Because of the lack of accurate info about the GPX 600R acceleration I have downloaded from YouTube an old video adding a stopwatch counter. From 0 to 160 km/h it takes 10,8 seconds with very strong wind on the front. Cycle World magazine Ninja 600R review in Sep 87 issue calculated 9,4 seconds from 0 to 100 mph. Because the GPX 600R use the KZ overdrive gearbox designed in the 70s pushing the engine in 6th gear overdrive at 0.85 is not appropriate forcing to much the crankshaft and pistons. Only 5th gear with engine sprocket at 16th or 17th should be used for maximal top speed and rpms. With such setup the 6th gear at 0.85 overdrive would be useful for route trips with lower rpms and less fuel consumption.