When I got the bike I thought that the engine was locked up. As it turns out, that wasn't true. When I tried to spin it forward, it was locked, but it spun freely when turned backwards. It seemed to me like something was in the cylinder. Click here to see what the culprit turned out to be.
After tearing the engine down, the heads and cylinders were masked off and blasted using glass beads. Following the bead blasting, they were cleaned up in a hot tank. I would NOT blast these parts without first masking any interior surfaces and oil passages. Think about it, you're bombarding these things with abrasive particles. Do you really want to pump a bunch of abrasives into your engine and then try to clean them out?
There is also the theory that some of the beads will embed themselves in the metal and resist cleaning, only to free themselves when the metal goes through a heat cycle or two. That's one reason I used a hot tank, which was really nothing more than a monster-sized dishwasher. (Disclaimer: Any ideas generated by that last comment are NOT the responsibility of Team YIKES! Motorsports, and we assume no responsibility for any type of domestic situation caused by the inappropriate use of common household appliances, no matter how well said appliances may work for the job at hand)
I didn't blast the case halves, there was too much to mask. For them I relied on wheel cleaner. Spray it on, hit the castings with a wire brush (by hand) and rinse. Repeat as needed. Carb cleaner can come in handy here too. I also used this method on the hubs, which can be seen on the wheels page.
Teardown: Buy a service manual before you start tearing into one of these things. Then study it before you get your tools out. It's not that it's all that difficult, there are just a few things to look out for along the way.
Some things I had trouble with on the teardown:
Pulling the transmission shaft bearing that's in a blind hole on the right side of the case. There is very little clearance to get a puller under it. I'm sure with the correct tool it would be easy, but I didn't have that tool. For some people this bearing has simply fallen out once the case was heated up. (If you are going to heat the case, do it in an oven to avoid warping anything.) I'm guessing this was on an engine that had already been rebuilt. On mine the bearing was still held in by punch marks the factory had applied. After trying to heat it, and buying a blind bearing puller that wouldn't work, I finally brought it in to Rod Rice, an instructor at Washtenaw Community College. He TIG welded a nut onto the bearing then screwed a slide hammer into that and pulled the bearing out. Worked like a charm.
The bushings that hold the bearings for the bevel shafts and ignition shaft are a pain too, if you don't have the correct tool. And unless you have worked on this stuff before, you don't have the correct tool. I ended up having a tool built.