500cc motor was always a good motor. better in later years but still good in early year with bushed timing side. Far superior motor to the ironhead sporty, power to weight is a big factor, but also parallell twin is, from an engineering perspective, superior to v twins. Witness the race wins at Daytona for the sportster versus the 500 Triumph in the 60's. Did HD even race at Daytona?? Did you ever see a sportster in a Desert race?