The clutch adjuster may be located at the lever or built into the cable.
Considering the amount of abuse they receive, motorcycle clutches rank right up there with stone axes and anvils in the reliability department. Nonetheless they are an expendable component and as such have to be replaced from time to time. Here's the lowdown.
How do I know I need a new clutch?
Unless you treat your motorcycle in an exceptionally brutal manner, catastrophic clutch failure is rare. Typically a clutch on the way out gives plenty of advance warning, so if yours craps out and leaves you stranded you've got no one to blame but yourself.
One sign the clutch is about to go kaput is a tendency for the engine to flare or rev a little bit, as the clutch slips when you engage the next gear during upshifts, particularly when you're hard on the gas or carrying a passenger. Another is for the engine speed to increase disproportionately compared with road speed whenever you try to accelerate, especially in the higher gears.
If you suspect your clutch is slipping here's a simple test. First make sure the clutch is properly adjusted. While in most cases this means adjusting the clutch-cable free play to factory-recommended specifications, there are some clutches that also incorporate a primary internal adjuster located at the throwout bearing. Your shop manual will provide the 411.
Next, find a quiet stretch of real estate and run the bike through the gears. With the transmission in high gear allow the bike to slow to 35-40 miles per hour and then snap the throttle open. If the engine races and the bike stays put, the clutch is due for replacement.
What kind of tools do I need to replace the clutch?
You won't need a whole lot of iron to replace a worn-out clutch. An OEM shop manual is a must, along with a set of common hand tools, a rubber- or plastic-faced mallet, a gasket scraper and a torque wrench. You'll also need a drain pan and, if you have a bike with Phillips-head screws on its clutch cover, an impact driver.
Toss in the standard expendable stuff like gasket sealer, a can of your favorite aerosol solvent and a handful of clean rags, and you'll be good to go.
As usual I'm going to hedge my bets and tell you that in some circumstances special tools may be required. For example, if your clutch uses a diaphragm-type spring you may need a spring compressor to remove and install it. Your manual will provide the details, and your dealer should be able to order any extra tools you'll need for the job. Last, unless you plan on replacing everything in the clutch stack, which isn't necessarily a bad idea, you should have a caliper or micrometer.
Preliminaries
Before commencing with the wrenching, do yourself a favor and give the shop manual a quick read. If nothing else you'll find out if any other tools are needed or if extraneous parts have to be removed before the clutch cover can come off. The manual should also highlight anything that's peculiar to your clutch. For instance, while many clutches use a given number of friction plates (all identical and all installed in the same way) some bikes have one or more plates that are slightly different from the rest and must be placed in a specific location.
I can't think of a single metric cruiser in current production that doesn't use some variation of the wet, multiplate clutch, so we'll focus the step-by-step procedure on that style of unit.
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.
I can't think of a single metric cruiser in current production that doesn't use some variation of the wet, multiplate clutch, so we'll focus the step-by-step procedure on that style of unit.
This is one job that can get a little messy. | 
The dowel pin fits into the shouldered hole; the one from this Sportster cover has already gone south. |
Loosen the coil springs like the ones on this Ducati clutch a turn or two at a time to prevent warping the pressure plate. | |