THE CRANK SHIM RANT. What is a crankshaft shim? To start with it's not really a shim. A shim is a piece of material used to make something level. The part used in the bike is a thrust washer to control crankshaft endplay. All the manuals refer to them as thrust washers or an end bearing while the mechanics refer to them as "shims". Why, I don't know. It sits behind the the main seal and around the crank end. So what about it? If you push the crankshaft in while doing this job the "shim" will fall into the engine. That's bad! Some people take the front cover off and brace the other end of the crank from moving. To get the shim out you will have to take the lower engine down. That's really bad! Pictured on the left is the front shim. You can easily see if it comes off it's pins.

Above is the rear thrust bearing(shim). If your you drop one of the shims, this is the one that will do you in. It sits on the other side of the main bearing and is held in just like the front shim with two pins. The shims don't really fall off but rather spin around and doesn't line up. If this happens to you, your in for a total tear down when you tighten the flywheel down. Here's a shot of one if you screw it up. This is a picture from the inside of the left jug.