Clutch slip

A tough question I know but hopefully someone can give me a few hints and tips.... I've read so far clutch slip can be caused by a number of things.

Anyway, I got my Mille last tuesday so I've only been able to give the bike a couple of runs. After bringing the bike home I found that there was pretty much zero clutch on the lever, so I bled the slave cylinder and loads of air came out. Fluid was low and pretty old looking.

First couple of ride outs were very slow as this is my first 1000, so steady away. Today I changed the oil and filter, replaced with semi-synthetic silkolene.

Feeling a tad more brave and decent weather this afternoon I gave the bike a little more throttle (and to check oil level)... anyway I noticed theres minor clutch slip through the gears when winding it open, the bike has done 20,500miles (2001)

What would be the first port of call for things to check? I have a feeling the slave cylinder could have a slight leak as theres evidence of some dried on fluid underneath it. I don't want to buy a full set of plates if it doesnt need it. I was wondering if I should give the plain plates a rough up with emery? Or I was wondering if the slip is just due to fresh oil?

Just read all that, from your last post are you thinking your "PPC check valve" is faulty?

I hadn't thought of that as I wouldn't have expected it to, I don't think I was accelerating THAT hard. It did feel exactly like clutch slip problem is being able to try it WOT in top as I expect your shifting on a bit!!! This was probably in 3rd/4th.

Used the bike for work today, the slip seems to be most obvious in 3rd gear but doesnt do it in top with wide open throttle?

Right guys, I've sorted out my clutch slip.

I've read bikes around 2001 had a badly machined clutch pressure plate which causes high spots on the metal plain plates. Took the clutch apart and thats exactly what I found.

So I machined the pressure plate square and it's solved the problem. I'd be happy to do anyone elses if they needed it doing for a small fee!

I've put some EBC springs in and just fitted a "factory racing" slave cylinder so it's lovely and light and seems 100% now.