ST1100 clutch engages in last 10% of travel

[Bigalone]

I just bought a 1993 ST1100 with 21000 miles on it. The plastic is banged up, but the brakes seemed good, the tires were good, the suspension seems okay, and it was only $800 so I figured why not. The PO had just flushed the clutch fluid and changed the oil.

Today I took it out for a few hours of highway driving. When I first got on, the clutch disengaged pretty quickly, with the lever only about 20-25% in. According to what I have read here, that's pretty standard. But by the time I got home, only ~50 miles later, the clutch was only biting in the last 1/2" of travel of the clutch lever. When I let the lever out, I have to let it out almost the entire way before it catches at all. I'm worried that the next thing that happens is that the clutch start slipping.

What could this indicate? I have read through the forums here and everyone says "bleed the clutch fluid". Well, the PO says he just did that, and I can verify that the clutch fluid is completely clear and the reservoir is full. What's the next step?

TY all, and I did enjoy my few hours of driving this morning.

 

[jfheath]

Welcome to the forum from the UK.

Check the brass bush in the clutch lever. Remove the lever. (Note that the nut on the bottom of the bolt under the lever is a lock nut. Remove that before unscrewing the bolt itself). Take out the brass bush without rotating it. Note where the blind hole is in the side bush. The push rod in the master cylinder should have been inside that hole. If they don't align, then that was the problem.

Reassemble and make sure that the push rod goes into this hole. Mark the top of the bush with a felt pen to help you to see where it is when the lever is replaced in the bracket.

Of course, it may not be this, but the symptoms match and it is a very cheap fix !

If this is the cause, it is because the lever has been reassembled with the pushrod pressing against the side of the brass bush, rather than properly seated in the blind hole. The result is that the clutch lever usually feels pretty tight and is already pushing a little on the slave cylinder. The compensation port in the master cylinder is therefore closed, so as the clutch fluid heats up in the slave cylinder, due to engine heat, it expands and has nowhere to escape, so it pushes in the slave cylinder even more. And yes, the result is eventually as the engine gets hotter, the the clutch will disengage and slip.

There is a fair chance that the previous owner had air in the clutch hydraulic line and didn't notice this problem. Sometime after bleeding it he noticed that the clutch wasn't biting properly, thought it was a serious engine fault and decided to sell.

 

[Obo]

@Bigalone welcome to the forum!

 

[Slydynbye]

What jfheath said plus check to see if the Clutch hose has an extra insulating sleeve on it down where it gets heat from the engine, if the hose was replaced sometimes they don't put that sleeve on.

 

[CYYJ]

Check the brass bush in the clutch lever.

Exactly. That is the most common cause of ST 1100 clutch issues. The brass bushing simply wears out from the steel pin pushing in on it.

Here's a link to a post showing a picture of the bushing: Click Here. That whole thread is worth browsing through, scroll up to the top to read it from the beginning.

Michael

 

[Upt' North]

They've already got you covered Bigalone, welcome from Northumberland, England.
Upt'North.

 

[Bigalone]

Thank you so much, friends! This bike is really fun, I'm enjoying it. Just hoping that I spend more time on it than under it!

 

[CYYJ]

Just hoping that I spend more time on it than under it!

If the problem is that the bushing is worn out, that is a quick, easy, and inexpensive fix. If you need to order a new bushing, check and see if the rubber boot that covers the plunger that pushes on the bushing has perished (it probably has) and order a new boot at the same time. Then pack the new bushing & boot with grease before installing the new parts.

Michael

 

[Uncle Phil]

Check the fluid level in the clutch master cylinder and take a look at the clutch slave cylinder.
If it is low on fluid or the slave cylinder is leaking, you might experience those symptoms.

 

[Walleye]

Bigalone
Ehh Bigalone, the symptoms you've described are just the opposite of what I have experienced with the worn bushing and pushrod. The clutch will engage closer and closer to the grip til it stops disengaging when fully pulled in, the rod has bored out the bushing. It is worth inspecting and applying grease. A local Honda shop has them in stock as they are a common part used in many models, I bought 2 as they were inexpensive enough to save a hassle down the road. Try Phils approach.

 

[PmodelinUS]

Well thank you everyone for the good advice. I was having the same issue. So I pulled it apart and my brass was very worn. I do have 67k on a 93. Just over 12k is me. Anyways I ordered the parts brass, pushrod, and a new boot. Put them in tried it out and yeah very little difference. So what's next?

 

[Bigalone]

Welcome to the forum from the UK.

Check the brass bush in the clutch lever. Remove the lever. (Note that the nut on the bottom of the bolt under the lever is a lock nut. Remove that before unscrewing the bolt itself). Take out the brass bush without rotating it. Note where the blind hole is in the side bush. The push rod in the master cylinder should have been inside that hole. If they don't align, then that was the problem.

Reassemble and make sure that the push rod goes into this hole. Mark the top of the bush with a felt pen to help you to see where it is when the lever is replaced in the bracket.

Of course, it may not be this, but the symptoms match and it is a very cheap fix !

If this is the cause, it is because the lever has been reassembled with the pushrod pressing against the side of the brass bush, rather than properly seated in the blind hole. The result is that the clutch lever usually feels pretty tight and is already pushing a little on the slave cylinder. The compensation port in the master cylinder is therefore closed, so as the clutch fluid heats up in the slave cylinder, due to engine heat, it expands and has nowhere to escape, so it pushes in the slave cylinder even more. And yes, the result is eventually as the engine gets hotter, the the clutch will disengage and slip.

There is a fair chance that the previous owner had air in the clutch hydraulic line and didn't notice this problem. Sometime after bleeding it he noticed that the clutch wasn't biting properly, thought it was a serious engine fault and decided to sell.

I checked it, and the pushrod was in the hole. No luck here.
It's still possible that the bushing or pushrod is worn, but if that were the case I would expect the clutch to disengage late in pulling in the lever, rather than early.
I'll try replacing the bushing since I have it -- but is my next step to replace and/or rebuild the primary and secondary hydraulic cylinders?

 

[jfheath]

Worn seals or air in the system will result in a lot of lever travel before disengaging. But crud in the master cylinder may be an issue if fluid hasn't been changed at least every two years.

Is it the original lever, or has it been replaced with after market ?

Someone once came to me to check out his front brakes which were locking. It turned out he had replaced the master cylinder piston/spring set with brand new. But not a Honda OEM service kit. The new push rod turned out to be a fraction too long. Maybe ...

Grit at either end of the push rod would produce the same issue.

Is your compensation port clear? This is the tiny, almost invisible hole underneath the silver cap at the bottom of the reservoir.
If poking this, make sure that the piston is fully returned - the primary seal will be directly beneath that hole if it isn't fully returned and poking will damage the seal. But if it is clogged, you will need to take the master cylinder apart anyway.

Reason for suggesting this is the same as the suggestion that the plunger might not be seated in the hole of the brass bush - ie the build up of pressure cannot escape through the port. Each time you pull in the lever, a little new fluid will be pushed into the line. When you release the lever, surplus fluid normally escapes through that tiny hole - the compensation port. if it can't, your lever will be tight and dis-engage early. Also as heat builds up, fluid expansion will not be relieved through that port with the same result.

So a service kit for the master cylinder may have to be the next step. Ensure the bore is clean too. Brake fluid is an excellent cleaner. No abrasives, just brushes and wood / plastic toothpics if the corners are gunged up. And a probe for the compensation port? - a primus stove 'pricker' or a top E string from a steel strung guitar.

Ensure the new seals go in flared open end first - the most difficult way. Use only clean brake fluid as a lubricant. Not oil or washing up liquid.

And do yourself a favour. Buy a Honda service kit.

But before any of that, just make sure that your clutch reservoir is not full to the brim. It should be filled to the max line. No more.

 

[Bigalone]

Worn seals or air in the system will result in a lot of lever travel before disengaging. But crud in the master cylinder may be an issue if fluid hasn't been changed at least every two years.

Is it the original lever, or has it been replaced with after market ?

Someone once came to me to check out his front brakes which were locking. It turned out he had replaced the master cylinder piston/spring set with brand new. But not a Honda OEM service kit. The new push rod turned out to be a fraction too long. Maybe ...

Grit at either end of the push rod would produce the same issue.

Is your compensation port clear? This is the tiny, almost invisible hole underneath the silver cap at the bottom of the reservoir.
If poking this, make sure that the piston is fully returned - the primary seal will be directly beneath that hole if it isn't fully returned and poking will damage the seal. But if it is clogged, you will need to take the master cylinder apart anyway.

Reason for suggesting this is the same as the suggestion that the plunger might not be seated in the hole of the brass bush - ie the build up of pressure cannot escape through the port. Each time you pull in the lever, a little new fluid will be pushed into the line. When you release the lever, surplus fluid normally escapes through that tiny hole - the compensation port. if it can't, your lever will be tight and dis-engage early. Also as heat builds up, fluid expansion will not be relieved through that port with the same result.

So a service kit for the master cylinder may have to be the next step. Ensure the bore is clean too. Brake fluid is an excellent cleaner. No abrasives, just brushes and wood / plastic toothpics if the corners are gunged up. And a probe for the compensation port? - a primus stove 'pricker' or a top E string from a steel strung guitar.

Ensure the new seals go in flared open end first - the most difficult way. Use only clean brake fluid as a lubricant. Not oil or washing up liquid.

And do yourself a favour. Buy a Honda service kit.

But before any of that, just make sure that your clutch reservoir is not full to the brim. It should be filled to the max line. No more.

"But before any of that, just make sure that your clutch reservoir is not full to the brim. It should be filled to the max line. No more."

Oh, that's a good one -- I think it *is* full over the line. The PO had flushed it, and it's so full that I can't even see the fluid line in the watch glass. I'll try pulling some fluid out.

 

[PmodelinUS]

So to remove fluid try a syringe or baster works well. An easy way to enshure the push rod is seated correctly in the bush is to temove teh master cylinder from the bar. Teh back is open and makes it easy to see if it's in the hole. Found that out lst night doing this.

 

[jfheath]

Wrap it with rag to catch the. ..... Sorry, too late ?

 

[PmodelinUS]

Is this what you mean by a bit dirty? ,

 

[PmodelinUS]

I want to thank the academy, utube, Honda service manual, and not having the common sense to not try fixing something new. Probably took me 5 times too long.thanks to bigalone for asking the question in the first place. I now have a very nice functioning clutch 2 weeks before a 900mile 3 day ride. Truly thanks to all.

 

[Bigalone]

Worn seals or air in the system will result in a lot of lever travel before disengaging. But crud in the master cylinder may be an issue if fluid hasn't been changed at least every two years.

Is it the original lever, or has it been replaced with after market ?

Someone once came to me to check out his front brakes which were locking. It turned out he had replaced the master cylinder piston/spring set with brand new. But not a Honda OEM service kit. The new push rod turned out to be a fraction too long. Maybe ...

Grit at either end of the push rod would produce the same issue.

Is your compensation port clear? This is the tiny, almost invisible hole underneath the silver cap at the bottom of the reservoir.
If poking this, make sure that the piston is fully returned - the primary seal will be directly beneath that hole if it isn't fully returned and poking will damage the seal. But if it is clogged, you will need to take the master cylinder apart anyway.

Reason for suggesting this is the same as the suggestion that the plunger might not be seated in the hole of the brass bush - ie the build up of pressure cannot escape through the port. Each time you pull in the lever, a little new fluid will be pushed into the line. When you release the lever, surplus fluid normally escapes through that tiny hole - the compensation port. if it can't, your lever will be tight and dis-engage early. Also as heat builds up, fluid expansion will not be relieved through that port with the same result.

So a service kit for the master cylinder may have to be the next step. Ensure the bore is clean too. Brake fluid is an excellent cleaner. No abrasives, just brushes and wood / plastic toothpics if the corners are gunged up. And a probe for the compensation port? - a primus stove 'pricker' or a top E string from a steel strung guitar.

Ensure the new seals go in flared open end first - the most difficult way. Use only clean brake fluid as a lubricant. Not oil or washing up liquid.

And do yourself a favour. Buy a Honda service kit.

But before any of that, just make sure that your clutch reservoir is not full to the brim. It should be filled to the max line. No more.

How do you feel about the K&L rebuild kits?

 

[jfheath]

How do you feel about the K&L rebuild kits?

Indifferent really. I wouldn't know. Since I started motorcycling again in 2000 after a 20 year absence, I just buy the OEM stuff. 'cos I have more money than I had when I was a 'youngster'. I no longer have problems with things not working, breaking, not fitting properly, wearing out early etc. So I never really experiment with other kit - unless I am forced to.

The only time I came across someone who had a rebuild kit recently - his front brake's were locked solid. Brand new aftermarket rebuild kit fitted. Plunger was a fraction too long.