Choose the spot where you want the zerk, and center punch the spot to drill the hole. Put it where the zerk will be easy to reach and won't contact wires, etc., when the handlebars are turned.

Drill a hole with the appropriate size bit for the tap you are using, based on the size of the grease zerk. I chose a 6x1.0 zerk, mainly because I have metric taps at home. I decided on the short straight zerk.

Use a drill/tap chart. 6 X 1.0 calls for a 5.2 mm drill bit (.2047").

The closest thing in my drill case was a 13/64 (.203"). This is close enough. You can use a slightly smaller bit, you just have tap slower/ more carefully. Much larger than recommended and you risk the threads not holding.

Use a nice sharp bit. This minimizes shavings, and cuts a lot better.

You may want to use a pilot bit first – I drilled a 1/8" hole as a pilot hole. Do your best – keep the shavings out of the head.

Next after cleaning up all the shavings, tap the hole. Use oil, preferably cutting oil, on the tap. I use tap-magic at this time. Cutting oil makes the threads cut easier and cleaner (no tear-out). This is important for good threads. Also, the oil keeps the shavings on the tap, out of your steering head bearings.

NOTE: If you have never used a tap to make threads, you should practice first. Use a piece of mild scrap steel, about 1/8" or so. GO SLOW. Continuously back out the tap every ¼ to ½ turn, whenever it starts to turn hard – this clears out the chips.