I'm in the process of replacing the wheel bearings in my 550 and, of course, need to get the retainers out. After searching around here for hints and tips, I went with the metal bar design:
http://forums.sohc4.net/index.php?topic=40052.0A length of 3/4" wide steel and a couple of 4mm nut/bolt combos and it was ready. It worked great for the front, but the back was having none of it. Try as I might I couldn't get the rear to turn. And, yes, I know it's a reverse thread and I drilled out the stakes. That wasn't the problem, it was just on really tight. With a lot of force the bar would flex and the screws would pop out of the retainer.
While pondering my options I remembered an article I had read in a Classic Motorcycles magazine (I think that's the title) where a guy made a pin spanner for a shock absorber from an open end wrench. Find a wrench of the appropriate size, drill two holes the correct distance apart through the side of the wrench, insert some kind of pin and you're ready. I started looking around and grabbed the biggest open end wrench I had, a 1-5/8". Some measuring, some drilling, some tightening yielded this:
The bolts are still 4mm and they have 7mm heads, which fit perfectly in the holes on the rear retainer. And you know what? It still wouldn't budge. I ended up whacking the other end of the wrench with a hammer to loosen the retainer, but after a about a 1/2 turn I could spin it out with my fingers. I know not everyone has a 1-5/8" open end wrench laying around (I'm not sure why
I do), but maybe this will give you some ideas.
~john