TIMING TIPS FOR THE 1.6
Lots of people have asked for these, so I finally wrote them down. Please read entire mess before starting. Not everything is in perfect chronological order.
Most early '5 engines can benefit from advancing the ignition timing.
Your timing light gets hooked up to the number one (closest to the front) spark plug wire. You can get +12 volts from the blue connector located near the front of the driver’s side wing. You can ground the negative lead of the light to the cam cover.
There is a diagnostic box located near the top of the nearside shock mount. This box is about an inch square and is black in color. Open the lid and you will find a little map of the terminals in it. Use a paper clip or piece of wire to jump the GND and TEN terminals together. You want to do this after warming up the car to normal operating temperature. With the jumper installed, your idle should be about 850 RPM. If it is incorrect, adjust it with the idle air bypass screw located on the throttle body. The screw is under a black rubber cap. Clockwise lowers the idle, CCW raises it.
Once you have the idle corrected, you can check the timing. Leave the jumper installed. There is a notch on the crankshaft pulley that should line up with the 10 degree mark if nobody has messed with the timing in the past. The marks are found on the nearside front of the timing cover.
At this point you have to find the cam sensor. The sensor on a 1.6 engine is located at the rear of the cylinder head on the inlet side. you will find a round object with an electrical connector on it. This is the sensor. It is about 3 1/2” in diameter. There is one bolt with a 12 mm head on it that is the hold down. Use a 12 mm box wrench to loosen this bolt so that you can rotate the sensor to make adjustments. Many people have suggested that a Sumo wrestler from the factory tightened this bolt 
I recommend scribing a line from the head to the cam sensor before you move anything so that you can always return to stock without dragging out the timing light again.
Loosen the hold down and rotate the sensor. Remember that every mark is two degrees. Most '5s can get away with 14 degrees on regular or mid-grade fuel. Once you have set the timing where you want to try it, lock down the hold down bolt and reset the idle speed to 850 RPM, because it will probably have increased as you advanced the timing. After you get the idle speed correct, pull the jumper lead out, disconnect your light and go for a test ride.
Timing tips for the 1.8 (94>)
These tips are meant to be an addition to the tips for timing the 1.6 (early) cars. Basically, there are only a few differences. The most obvious one is that the cam sensor has been moved to the driver’s side rear of the cylinder head. Follow the “hump” in the valve cover on the passengers side back to the cam sensor. It is a round object with an electrical plug mounted on top of it. Same as the 1.6, it has one bolt with a 12mm head acting as a hold-down. The other (important) difference is that there are two marks on the crankshaft pulley. Contrary to what Mazda’s shop manual says (possibly corrected by now), you have to use the yellow mark, NOT the white one. Same specs apply as given in the 1.6 directions. Remember to scribe a mark before rotating the cam sensor, to guide you if you need to head back towards stock.
How To guide downloadable here for Owners Club members.