Wet it down and soak it in conditioner or cholesterol (you can find it at Sally's or Wal-Mart in the ethnic hair section)
for like 5 minutes. It will help to soften all the dead flaking skin. Then rinse his mane and wash it with shampoo and be sure to scrub really well. Rinse it really, really well. If you don't feel like you've gotten all the shampoo residue out you can rinse with a little white vinegar it will help cut the suds. If the scurf continues to come back try a moisturizing spray like Health Hair Care
daily when you're grooming. Make sure to dilute it to the right ratio or it will get greasy and attract dust and dirt.