[Aussie Mike]

Pull off the dizzy cap and see if the rotor turns when you crank the motor. Could be a broken distributor gear.

If that's OK look and see if you have fuel, spark and compression. A quick check with a compression tester will tell you the state of each of your cylinders.

Pull a plug and laying it on the rocker cover with the lead connected and crank the motor. You should see a nice blue spark across it.

With the air cleaner off have a look in the top of your carb open the throttle and see if the accelerator pump shooters squirt fuel. (don't crank the engine whilst doing this as I've seen people lose their eybrows to a ball of flame).

Cheers