Clutch not fully engaging, please help me!!

Black fluid in the reservoir on any bike tends to indicate the master cylinder seal has degraded (fine black rubber particles in the fluid). My K1300GT had pitch black fluid in the reservoir when I got it 5 years ago but I replaced it with Vitam LS (the BMW red stuff) and it worked OK. It came out darkish again once more and, after using up the small bottle of Vitam, I started using the green LHM+ (Light Hydraulic Mineral Oil) designed for car hydraulic steering/suspension and brake systems (e.g. LHM Plus Hydraulic Fluid - as you can see its cheap) and it's been fine ever since. Best to use the "+" version as its pour point is lower.
I wouldn't assume it's got brake fluid in - it could be that someone used an ordinary mineral oil. If you can bleed it up OK (bit of a faff - definitely best to back-bleed by pushing up with a syringe from the bottom - and you need to replace the blanking screw with a nipple (like this Clutch slave cylinder bleed nipple) and cap) and get it working properly, and it stays working for a couple of months, you may not need to worry about damaged seals.

MauK1200 said:

Thank you so much.... is this Green LHM+ something like the VW Power Steering Fluid which is also mineral oil???? I have already ordered Shimano fluid but would be nice to know if this other fluid could be compatible. For my Audi I use CHF22... green mineral oil.

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I think most of the "CHF" products are synthetic oils. I don't know specific reasons why they can't be mixed with mineral oil (like you can with mineral and synthetic engine oils) but there're mixed opinions in the car forums about it, so probably best avoid it just in case the one you pick is somehow different. Don't know about the VW stuff but suspect, if its definitely a light mineral hydraulic oil, it should be fine. I use LHM because its definitely a light hydraulic mineral oil (the clue's in the name!).
Btw, you can tell if someone's put DOT4 brake fluid in your clutch mech as its water soluble and not miscible with oil. Try dropping some into water - if it floats, it's oil, if it fairly rapidly dissolves, it's probably DOT4. Likewise, try dropping some into oil - if it sinks, it's probably DOT4 and if it dissolves its probably oil. Of course it could be DOT5, which is silicone based but that's unlikely.
To bleed the clutch (once you've put a 5mm bleed nipple(with cap) in the slave cylinder) you'll need a 50ml syringe (could be bigger but smaller allows you to apply more pressure as the holes in the nipple are small) and some 3mm bore clear neoprene tube (like model engines use), and ideally a mate with another syringe ready to suck it out of the reservoir to stop it overflowing. Also not a bad idea to put PTFE tape around the threads on the nipple to stop air getting in down the thread. I tend to fill my lower syringe and tube, crack the nipple so fluid is coming out and so there's no air in the nipple (put a rag under it to catch it) fit the tube to the nipple, draw 50mm of fluid OUT just to get any air out of the top of the slave cylinder, let any bubbles rise to the top of the syringe, then push fluid through. Just like brakes you can also get tiny bubbles out of the top of the system by tying the clutch lever back overnight and then repeatedly pulling it in and letting it go; also by flicking the pipe with a screwdriver or similar to dislodge fine bubbles. It can even help to lean the bike to the right overnight so the pipe is more vertical. With clean fluid in, you can see streams of fine bubbles rising up in the reservoir. Given the blackness in the reservoir you might want to repeat the bleed after a month or 2 of use. I've found, once you've got all air out of the system you can usually bleed it downwards like a normal brake bleed (a vacuum bleeder helps). I do it about once a year on the GT and the S.

If the clutch worked fine before, though, it does sound like maybe, in doing the clutch basket change, you've changed something else that's stopping it freeing off - and your fluid bleed can wait.