This tool is used to compress certain types of diaphragm clutch springs so the snap ring can be safely removed.
Removing the clutch cover
Because the new clutch will be somewhat thicker than the old, worn one, start by backing off the clutch cable adjuster. That way when you install the new clutch it won't be preloaded against the throwout mechanism. If your bike uses a hydraulic clutch actuator special procedures may be required, so check your manual.
Drain the engine oil, then position the drain pan under the clutch cover and remove the cover bolts, noting their length and location in the case. If you're the forgetful type make yourself a cardboard template that mimics the clutch cover to store them (see Tech Tip June '04, "Board Games").
It's highly unlikely the clutch cover will pop right off. Some have pry points cast into them so they can be levered off (your manual will point them out). But unless you know that to be the case, resist the temptation to jab a screwdriver in there and start worrying the thing. All that'll do is gouge the gasket surface and ensure future oil leaks.
One way to remove a sticking cover is to tap firmly around the periphery with your soft mallet-the operative word here being "tap." The idea is to break the bond between the gasket and the cover, not bust a hole in the case. If a few mellow taps won't loosen it, you might have missed a screw or two, so double-check.
The throwout bearing usually has a fairly loose fit in the pressure plate, so be careful not to drop it. Note that this one also has a primary clutch adjuster built into it (the threaded rod sticking up). If your bike uses a similar setup make sure it's backed off before you dismantle the clutch.
Once the cover's loose carefully work it off the engine, watching for any dowel pins that may come off with it, and put it aside for the time being. If the dowel pins did come out with the case, place them back into the crankcase. With the cover out of the way the next order of business is removing the clutch pressure plate.
The pressure plate will be fastened to the clutch with either several coil springs and bolts or one big diaphragm spring and its retainer. Loosen the coil springs a turn or two at a time in an alternating pattern until all the tension has been removed from the pressure plate. Clean and set the springs aside.
If your clutch uses a diaphragm spring read through the appropriate section of your shop manual before trying to remove it, just in case special tools or procedures are required.
Before you remove the pressure plate take a moment to check its orientation. In most cases the plate isn't keyed to the clutch in any particular way so long as the bolt holes line up. But occasionally you will run into one that's indexed to the clutch drum. In those cases failure to get everything lined up will result in a series of frustrating experiments in which you rotate the pressure plate one bolt hole at a time until everything is finally in place and the plate seats properly. If you're unsure mark the pressure plate and the clutch drum with a Sharpie or dab of paint so everything will go back in the same place.
Ease the pressure plate off the clutch, keeping a sharp eye out for the throw-out bearing that's probably going to drop to the floor. Wipe the pressure plate clean and inspect the face for damage. If the plate is heavily scored replace it, but I wouldn't expect to find anything serious unless the clutch suffered a calamitous failure.
The friction plate is on the left, the steel on the right.
With the pressure plate out of the way you can start removing the clutch plates. All multiplate clutches use two types of plates: fiber or composite friction plates, which engage the clutch's outer drum and rotate with the engine, and steel plates that slot into the inner hub and turn with the transmission input shaft.
While I'm sure there's a bike out there that'll make a liar out of me, the first plate in the stack should be a friction disc. Before yanking it out note the way the disc is installed. In some cases radial grooves are cut into discs at a tangent; this allows oil to escape from between the plates as they engage. If that's the case and the plate is installed backward, centrifugal force will tend to trap the oil between the plates and prevent them from seating, possibly causing the clutch to slip.
The typical wet multiplate clutch. That odd-looking riveted plate in the middle of the stack is an anti-judder plate.
The next one in the stack will be made of steel. Normally the steel plates can be put in any which way, but make a note of how they're oriented just in case. Continue to remove the plates, laying them out in order so you know which way they'll go back in when it's time to reassemble everything. If you find the plates a little reluctant to leave their nest, a piece of stiff wire bent into a hook will help pry them loose. Occasionally you'll find some oddball pieces in the clutch; anti-judder springs or plates are always popular. As these may or may not need to be installed in a given direction pay close attention when you remove them. With the plates removed, clean and inspect the hub and drum.