If the fluid in the clutch master cylinder reservoir is dark, or the clutch lever feels soft and spongy when pulled in, it may be time to bleed (or replace) your clutch system. Flushing and bleeding the system will prevent bad fluid from wreaking havoc within your clutch master cylinder, and will ensure a firm, positive clutch engagement. The task requires only a few small tools and is much easier to do than it seems.
Locate your clutch slave cylinder fluid fitting and attach your plastic hose and fitting. Be sure that the hose is long enough to reach your overflow bucket.
Open your clutch master cylinder cap and remove the diaphragm.
Suck out any fluid in the reservoir using a syringe. This step is optional, but prevents contaminated fluid from entering the clutch line.
Fill the fluid reservoir and lightly tap the line, lever and reservoir to free any air bubbles trapped in the fluid. Keep the fluid reservoir filled to prevent air from entering the line.
Pump the clutch lever three to four times, then hold it in.
Open the fluid fitting on the slave cylinder a half turn. A small amount of clutch fluid should appear in the hose.
Close the fitting before the fluid stops moving and release the clutch lever.
Repeat Steps 2 to 4 until the fluid's color is consistent and without air bubbles. Fill the fluid reservoir as needed.
