Dan,
The newer ones are 14/47. Not sure what the 89 was but I thought is was the same. Depending on your riding area, sometimes a 500 works better with taller gearing like the 14/48 you are talking about. It doesn't really lose power down low, just makes 1st gear taller so is harder to ride extra slow in extremely tight riding spots. The 500 has so much torque that taller gearing can tame the wheelspin/wheelie tendency and turn it into more traction. My stock was 14/47 and I run a 14/48. Hope this helps. Cam.