Mine is not the Metal on metal type. It has a rubber bellow, there is no fluid escaping or any air hissing. :puzzled:

I would check the clutch pressure plate bearing where the pushrod fits into the pressure plate. I have seen it before, the bearing partially siezes and spins the pushrod which twists the piston in the slave cylinder which then retracts and allows air in. the bearing should be comlpetely free.

dave

Ive just fitted the Cornerspeed Slave cylinder ,I did not have to change the pushrod on my 98 996.There was a small rubber washer that sits between the slave and the casing that the pushrod sit through,if thats been split it could allow air in maybe. Sounds like a leak of some kind, maybe try a splash of weak fairy liquid and water mix around the joints to see any bubbles appearing. 4D

I might be wrong but i think the slave cylinder is a sealed unit in its own right, it doesnt need to be bolted to the engine to work. Of course if you operate the clutch lever without the cylinder bolted to the engine then the piston will pop out. All the rubber bellows things does is stop chain lube etc getting all over the piston. Mine split and dropped off ages ago. I must replace it one day!

I had a problem on my monster 900 like yours. I even bought a new master cylinder. And slave cylinders. Borrowed two of Nbs. They were fine.
There was still air trapped in pipe. You need to tip the bike over to the right as far as fluid wont pour out and bleed. It works everytime for me since at least 3 times as I tried new hoses since. It been good now since July:)

I had the same problem but I found out the hard way, the push rod could be spinning and damaging your slave cylinder , this will course your fluid to go black in the master cylinder to because of the o-ring rubbing in the slave cylinder.

Like Albie my money is on air in the system... It can be a right pig to bleed it completely. Make sure you use a brand new unopend bottle of fluid too. Brake fluid absorbs water as it sits on your garage shelf.

Darren

Hmm
I had a similar problem on the 996 and when Nelly stripped it down at the 12K service he found a seized clutch pressure plate bearing and a snapped push rod as it goes through the casing, still workwed but when I lost pressure I just pumped it a few times and all worked nearly fine but seemed to free of if parked for a while which makes me think it was a sticking pushrod?
Poss caused by the split rubber?

Nelly will sort for certain when it gets there, worked for mine.