Yeah, I'd say that's a bit off.
My KDX200 has exhaust port opening at 96 degrees after TDC (83 when power valve opens), and the transfer intake ports at 120 degrees.
The following is from Eric Gorrs site and may be useful:
Tuning for Specific Powerbands
I've designed the chart shown below, to give you some general guidelines on different powerbands and the changes required to the individual engine components. For specific recommendations on your model bike, refer to the chapters on tuning tips.
Component: Cylinder Head
Low To Midrange: 9.5:1 compression ratio, squish band 60% of bore area
Midrange and High-Rpm: 8:1 compression ratio, 40% squish
Component: Cylinder Ports
Low To Midrange: Exhaust port 90 ATDC, transfer ports 118 ATDC
Midrange and High-Rpm: Exhaust port 84 ATDC, transfer ports 116 ATDC
Component: Reeds
Low To Midrange: Dual-stage or .4mm fiberglass petals.
Compromise: Thick carbon fiber petals
Midrange and High-Rpm: Large area 30-degree valve
Component: Carburetor
Low To Midrange: Smaller diameter or sleeved down carb (26mm for 80cc, 34mm for 125cc, 36mm 250cc)
Midrange and High-Rpm: Larger carb (28mm for 80cc, 38mm for 125cc, 39.5mm 250cc)
Component: Pipe
Low To Midrange: Fatty or Torque
Midrange and High-Rpm: Desert or Rpm
Component: Silencer or Spark arrestor
Low To Midrange: Short, small diameter
Midrange and High-Rpm: Long, large diameter
Component: Ignition Timing Advance timing
Low To Midrange: Stock timing
Midrange and High-Rpm: Retard timing
Component: Flywheel
Low To Midrange: Add weight
Compromise: Stock flywheel
Midrange and High-Rpm: PVL internal flywheel
Component: Fuel
Low To Midrange: Super unleaded 93 octane
Midrange and High-Rpm: Racing fuel 105 octane