Originally Posted by modifyITall
OK so i have a 1999 Busa. We were out at a road in Naples right off of I75, and i let it go. Speedo said 220 mph and 6th gear was hitting the limiter. How fast was i really going? All that is done to the bike is i have a 41 tooth rear sprocket. No i dont have a picture or anything to show that thats what the speedo said but thats where it was.
Busa Speed Calc Tool
The error is different at different speeds.
One way to determine the error is with a GPS. Note the speed on the speedo at say 70mph the note the GPS speed. The difference between the two is the error at 70mph. Do this for 80, 90, 100, etc. Then you can determine whether the error increases with speed or not. Good ol' imperical test will net you the most accurate results.
You can also calculate how fast your bike should theoretically go at a given RPM in a given gear with a given final drive ratio (the chain and sprockets are the final ratio).
Here's the ratio's of a stock busa.
Primary = 1.596 (83/52)
1st = 2.615 (34/13)
2nd = 1.937 (31/16)
3rd = 1.526 (29/19)
4th = 1.285 (27/21)
5th = 1.136 (25/22)
6th = 1.043 (24/23)
Final = 2.352 (40/17)
You need to pick an RPM most probably the rev limiter 10,800 RPM.
...and you'll need the circumference of the rear wheel.
Click Here for a Site than can help calc your theoretical top speed.