NRG-500
The NRG-500 is the fastest bike in Grand Theft Auto: San Andreas. The bike is based on the Honda NSR500 as used by Valentino Rossi in the 2001 500 cc World Championship, hence the distinctive number 46 on the front and the very similar names. Since it's a racing bike, it also handles precisely. The NRG-500 can appear with one of three subtly different exhaust pipes and one of two different bodykits.
It is the bike which starts the NRG-500 Challenge at Easter Basin Dry docks.
Locations
It appears only in 3 places: In front of the bike school if you have all golds and in the warehouse in San Fierro docks, where it's associated with one of the vehicle challenges. Lastly there are two in a carpark on East Beach in Los Santos, the carpark has a spiraling ramp so its easy to spot one of the two.
The NRG-500 spawns at the Easter Bay Airport, in between the two southern most hangars near the Maverick. Jumping from the tunnel in the mountain, you can almost land exactly where it spawns. This is actually how many players find the spawning point.