[Dave Samson]

Either hook up an air/fuel ratio meter to your Oxygen sensor, if you have one installed, or hook up a 0 - 1V DC volt meter to the sensor and watch the numbers. Readings as low as 0.2 V indicate very lean, up to 0.9 V indicate very rich, idle should be around 0.4 - 0.5 V. The readings are only meaningful once the sensor has heated sufficiently and gone in closed loop. I use both methods.
Let me have your email address, I'll send you an some interesting reading on this subject.