Motorcycle Repair: Clutch fades on 86 Honda shadow, clutch master cylinder, clutch slave cylinder

Question
I have recently purchased a 86 honda shadow that is in pretty decent condition other then a few small things.  It recently ran out of clutch fluid due to a poor seal on the master cylinder, which has been corrected.  I have bled the system including bleeding the banjo connection at the master cylinder.  It will hold pressure just fine for 2-3 seconds but then looses it.  It was fine prior to it running low of fluid.  Any ideas as to what might cause this?

Answer
Pat, did someone look carefully at the clutch master cylinder bore inside? If there is corrosion or deep pits, the new seals won't be able to hold pressure. There are 2 bleed ports in the base of the reservoir that must be clean and clear, as well.

You might try putting a solid bolt through the lower banjo fitting, with the washers and see if you get some more feel that way. If so, then you could be having issues with the clutch slave cylinder seals, but they would be leaking and drooling down the engine cases, in most cases. If still spongy, then you still have air in the system or the master cylinder seals are not holding pressure due to seal/bore issues.

You need to bleed ALL the junctions of the hydraulic lines. Sometimes, a vacuum pump is better than pumping it out and down. Other people have rigged up big syringes with brake fluid to push it back up the line, floating the air bubbles to the top.

They are never easy to bleed....

Bill Silver