Clutch won't engage

I've owned a 92 ST1100 for 5 years, it was very well maintained and ran perfectly across the country. I've let it sit in my Mom's garage for the past few years, keeping the battery charged etc.

A year ago, when I was riding it, the clutch wasn't fully engaging when I came to a stop, ie, I had to keep the brakes on because the bike would keep moving forward with the clutch in. Now I'm back and need my ride to work properly, so I bleeded out the very dirty clutch fluid and saw plenty of air bubbles, but now they're gone and the fluid is clear, yet I still have no clutch.

It makes the rather loud CLUNK sound when I pop it into gear with the clutch lever engaged and it will shift up or down on the center stand without too much trouble, but the wheel won't stop spinning.

I did have an electrical issue and had to replace the regulator last time I was in town. Any thoughts?

As an addendum, while I hope and pray I find an easy fix to this problem, I've gone back out and repeatedly engage the clutch lever, I am still getting some air bubbles and a slightly dirty discharge is coming into the reservoir from the hose below. Maybe I just need to bleed it repeatedly?

Definitely worth the effort. Search the forums for this problem.

I've searched high and low, nothing quite compares to the problem I'm having. I just spoke with a mechanic that'll do a slave cylinder rebuild, which he thinks is the problem, so that's the next thing I'm going to research, although having pulled off much of the right side body work to see if I could get at all the bolts, it looks as though I would have to pull the muffler to get at the bolts for the slave cylinder.

On the issue of air bubbles, if I have the bleeder closed and all other connections tight but when I depress the clutch lever I get air bubbles on the reservoir, those are just occurring from the lever itself, not the line?

dont think it's elec problem.... just clutch system. Sounds like air not slave.

First, I'd redo the full bleed ( dot 4 is cheap ) and make sure all the crap is out. After that try strapping the cutch lever all the way in over night to make sure all air comes out of line at top.

Also I might change the engine oil as it may need it and it may help infreeing the clutch plates from sticking a bit from sitting so long.

trevtop said:

it looks as though I would have to pull the muffler to get at the bolts for the slave cylinder.

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That pesky third bolt is do-able without disturbing the exhaust, with just the right pushing, prodding, wrench, patience and bad words.
and agree with Tom above.

I think you really mean that the clutch isn't completely DIS-engaging - it's dragging, etc.

Sounds like you may have some air in the system, still. Try "reverse" bleeding. Using a syringe ( Ag store or from your Dr.'s office ) with some small ID tubing "screwed" into the tip, fill the syringe with brake fluid, invert the syringe and with the tubing up, eliminate as much air as possible by pushing in the plunger. Then push the lose tubing over the bleeder screw, loosen the bleeder screw, and force the brake fluid into the brake caliper. Hopefully any bubbles will rise upward and be released into the MC reservoir. Any trapped air wants to flow up, not down. This is why sometimes "reverse" bleeding works when the standard bleeding method doesn't. At least that has been my experience. And sometimes just filling the MC reservoir with fluid and opening the bleeder screw and letting gravity do it's thing can eliminate trapped air.

Sounds like trapped air in the system. Bleed the air from the banjo bolt as was mentioned above, I've found air gets trapped there.

You may have 2 problems. The air as mentioned and the brass bushing in the clutch lever. If the brass bushing is worn the clutch will not fully release when the lever is pulled. The clutch master cylinder piston is activated by a rod that wears into the brass bushing and will not go full stroke. Pull the lever off and check it. It's quick and easy and if it needs replaced it's only about $15. I think the nut on the lever is a lock nut and needs to be removed before removing the pivot screw.

Ron said:

You may have 2 problems. The air as mentioned and the brass bushing in the clutch lever. If the brass bushing is worn the clutch will not fully release when the lever is pulled. The clutch master cylinder piston is activated by a rod that wears into the brass bushing and will not go full stroke. Pull the lever off and check it. It's quick and easy and if it needs replaced it's only about $15. I think the nut on the lever is a lock nut and needs to be removed before removing the pivot screw.

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Seem to recall having similar quagmire with our '91 ST11 some years back - IIRC, the above ^^^ concept is spot on regarding the bushing, and was relevant to the final solution. I'll see if we have it in the log for that bike.

OKay!!! Problem has been solved!!! I was being to think I needed to change my oil and filter, and still probably should, but... I pulled the lever off, bushing looked fine so I wasn't too excited, but I squirted some 409 into the hole where the bushing would go, used a screwdriver about the width of the bushing and pushed it in several times and noticed the small bubbles were now big bubbles and it felt like I was finally getting some tension going, so I reinstalled the perfectly good lever and bushing, instantly noticed much greater tension as I pulled the lever and DIS-engaged the clutch, yes thank you for the clarification, kept priming it and the tension got stronger, so I started up Louisiana Red, pulled the lever, put it into first gear and NO WHEEL SPIN. Yes, my clutch is BACK!!!

Thanks for all the help and suggestions. Can't wait to get back on the road!

Hi neighbor. Me again. ignore my comment on your intro thread - you've already done it.

Has anyone tried high performance dot 5.1? I've got the problem with loosing the clutch in town when the bikes hot, a mate recommended the 5.1

You don't need 5.1, you need to bleed or the hoses have started to fail due to heat/use/age.

Mark said:

You don't need 5.1, you need to bleed or the hoses have started to fail due to heat/use/age.

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Maybe time to replace the hoses on that bike also.

No need for a different kind of brake fluid, Keith. Just replace your old with new.

Ron said:

If the brass bushing is worn the clutch will not fully release when the lever is pulled. The clutch master cylinder piston is activated by a rod that wears into the brass bushing and will not go full stroke.

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Yep, lever (the brass eye/pivot bearing), bushing and the little rod are often neglected... so is the little rubber boot (normally) covering the rod to protect it from the elements and keep humidity away from the innards of the master cylinder.
(BTW same concept/assembly exists on the brake side too...)

970mike said:

Maybe time to replace the hoses on that bike also.

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If anyone needs hoses at much less than OEM prices, check out : Brake Materials and Parts in Ft. Wayne. Talk to Scott.

They will copy your OEM hoses and also make stainless steel hoses much cheaper than anyone else can, I believe. The new custom hoses are pressure tested to 3,000 psi. They made new hoses for my ST1100 and I have just sent them the old hoses off a GL1100I I recently purchased to copy.

I fitted a new slave cylinder kit and the 5.1, an expensive replacement for the standard , oops.when I got the slave cylinder off it was full of crud, a bit like brown sugar. Cleaned all the components and refitted. Ran the bike until the fan kicked in,the clutch
worked, phew. I'll update if the problem arises. Cheers guys.

Keith.no1 said:

I fitted a new slave cylinder kit and the 5.1, an expensive replacement for the standard , oops.when I got the slave cylinder off it was full of crud, a bit like brown sugar. Cleaned all the components and refitted. Ran the bike until the fan kicked in,the clutch
worked, phew. I'll update if the problem arises. Cheers guys.

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Interesting that you ran the bike until the fan kicked in and the clutch worked.

I started with a clutch problem that I thought I solved without messing with the slave cylinder, but after riding it for a while I started having an overheating problem that led to the bike dying and I would have to charge the battery. Then I flushed the cooling system, fixed hoses, and changed the oil. I noticed after I changed the oil that the rear wheel was spinning even in neutral, which it hadn't done before. Could my overheating/fan not working be tied to my original clutch problem?