We get this one alot at work...
1. Pull the tank, adjust the compression cable, pull the sparkplug and squirt in roughly 1/2 to 1 cc of raw gas.
2. Put bike back together.
3. Set the fuel ta on prime, wait 2 minutes, and twist the throttle, TWICE.
4. Cross your eyes, stick out your tongue, pray, and hit the starter.

If it catches, set the fuel tap on run, adjust choke, adjust idle, go for a ride. Works about 80% of the time on older Japanese cruisers, dual sports, and dirt bikes.
If it doesn't catch, pull the carb, dismantle and clean ALL the orifices and passages with GOOD aerosol carb or contact cleaner. PJ1 or Berryman Chemtool are the best ones going right now. Odds are you still have a small piece of debris in the pilot jet circuit. Common to any older bike.
-WD
Odds are it is a problem with the decompression cable, lube, adjust, or replace if needed. If you don't have a maintenance book, get one. The specs are close enough to get you going again, then you can fine tune as needed by YOUR bike.