Not a drill, hell no, but a Dremel, yes!
The cylinder is nikasil plated (THIS IS IMPORTANT!) and you HAVE TO be careful with that. Always take away any sharp edges (At least on the horisontal lines of the port, vertical lines doesn't matter as much.) so the piston rings doesn't grab them.
Personally I soften the edges off a little with the Dremel, then I use a fine sandpaper by hand to do the finish.
I suggest you use the small roller sandpapers for the Dremel. They work best.
Never (And I mean NEVER!) make the exhaust port lower, always work on the width and height.
I also suggest you don't raise the exhaust much. 0,5mm too much might very well make it run like crap. Do the width first.
Widen the port about 1,5mm on each side (again, think about the edges not being sharp) but make sure the cylinder have "meat" enough so you don't end up with a hole straight through the material.
The exhaust port height is most picky. The best way (IMO) for a newbie to do it is to raise it successivly in small steps. Take about 0,5mm or smaller at a time.
That way you can feel if it's getting more power or not. Hopefully it'll get better as you raise it, but if you feel that it stops getting any better, then stop raising it.
If you don't feel like ripping the top end off several times just to get the port height right - and instead going for the "guessing how high the port shall be", then you will most likely end up with a very weak running engine. So take your time with it, it's definitly worth the hassle in the end.
