Strange clutch issue

[heavyd]

I am having a strange clutch issue that is getting worse and getting on my nerves.

Backstory: Early last summer I replaced the throwout bearing and since I was in there I took the clutch pack to a shop and had them replace the spring and dampener plate because I don't have a press. 1500 Miles later that clutch is slipping and there is metal dust in the oil filter. Built my own press and replaced all of the clutch plates and rebuilt the slave cylinder. I can't remember anymore if this started right away or a few k miles later, but the tension on the clutch lever seemed intermittently soft. That was all 15k miles ago-ish and now it isn't working right when I try to downshift from high gear at low rpm. If I downshift at 3k it's fine, under 2k and it won't shift. If I hold the lever in a bit there is  no pressure at all, if I then give it a shot of throttle I can feel the pressure come back against the clutch lever. In the last 1000 miles, it has also started not shifting into neutral at a stop while the bike is running, if I give it a shot of gas and keep some pressure on the shifter it drops in basically like I was driving it without a clutch.

I feel like I'm doing a poor job of explaining this....

I have bled at least a liter of fluid through the clutch trying to make sure there was no air, my next step is to drain the clutch fluid again and use a syringe to push the fluid from the bleeder up into the master. After that my only thought is to rebuild the master cylinder but I hate just throwing money at a problem.

Does anyone have any thoughts or theories?

Thanks

[heavyd]

Not that I expect it will change any answers, but just incase.

It is a 97 Standard with a windshield and tourer pack added when it was new. I've had it for about 22k miles and there are just under 70k total.

[Avanti]

I would clean and flush the clutch resistor, line and cylinder. If you have a vacuum pump, pull the fluid through the system to bleed all air out. Also check for leaks.  

[Jruby38]

Bleeding from the bottom up works better.  Does the bike shift into neutral the same hot or cold? I have a harder time finding neutral when it gets hot in traffic.

[Avanti]

Bleeding from the bottom up works better.  Does the bike shift into neutral the same hot or cold? I have a harder time finding neutral when it gets hot in traffic.

Yes you are correct, always bleed from the bottom.
Using vacuum pulls the fluid through much faster, which allows it to scrub the system cleaner and remove even the smallest of air bubbles. Small air bubbles will eventually find each other and become one or more large air pocket causing low presser in the system, which is not desirable. This would than cause the clutch cylinder to not have its full stroke at which time the clutch would no longer disengage.  
From the Manual.
Clutch will not disengage or motorcycle creeps with clutch disengaged
Air in hydraulic system
Low clutch fluid level
Sticking hydraulic system
Leaking hydraulic system
Warped plates.
0il level too high, improper oil viscosity or oil additive used.
So what oil is or has been used?
Where was the metal coming from?

[heavyd]

Hopefully I can answer all these questions.

I have been bleeding it with a vacuum pump, and pulled nearly a liter of DOT4 through it.
The only oil or filter that have been used since I have bought it are Honda OEM.
As near as I can tell the metal came from the clutch steels, the color was a match and there was some scoring on the plates. Once I replaced them the metal disappeared after the next oil change, there have been 4-5 changes since with no sign of anything.

The only reason I was thinking of pushing air through was hoping that doing it that way would push any air out ahead of the fluid.

I have only noticed an issue switching to neutral when it is hot, if the bike is still cold or shut off it is no problem at all.

The most confusing part for me is why the clutch pressure changes with engine rpm. Picturing in my head the way this system works, if I am not applying enough hydraulic pressure to overcome the spring everything should be tight in the clutch pack. If the engine rpm picks up, suddenly I have more hydraulic pressure at the lever, where did that pressure come from? I haven't moved the lever so the amount of hydraulic pressure vs spring pressure should be the same right?

I seem to remember reading somewhere in a post here that excessive bleeding can damage the master because it lets the plunger move beyond it's normal range. I can see how that makes sense but would that cause an issue like this?

[flash2002]

Just wondering, did you check the master bushing for wear, I know that when they wear it changes the clutch from working properly. It might have nothing to do with the problem but what if.

[Avanti]

If at this point we assume that the clutch lever bushing is not at fault, the clutch fluid does not leak and has no air in the system, than the next place I would check is the clutch slave cylinder. Is the slave cylinder working properly.

Check all the simple solution thoroughly first. 

Also, is it possible that the clutch assembly has come loose?

[heavyd]

I haven't checked the lever bushing, I can check that tonight. I'm not sure how I can check the slave cylinder, when I was replacing everything else, I did put new seals in the slave cylinder and greased the pushrod when it was going back together. I can't imagine how the clutch assembly could come loose with the nut staked on.

[Avanti]

Just wondering if the inner seal that keeps the engine / transmission oil out of the slave cylinder is leaking. This would put oil on the back side of the slave cylinder. If this happens maybe the cylinder is trapped between clutch fluid and engine fluid impeding the slave cylinder movement. Seems as though the cylinder would be able to push oil back past the seal or out weep hole, but at what rate? Not enough travel by the slave cylinder?

Still wondering about the metal in the oil issue. Did you have to replace parts that were worn or scored? How was the prior repair done incorrectly that caused it to fail?

Trouble shooting from a distance is poor at best.
Maybe you could get help from some one close by.

[Avanti]

Check to see if the bleed port is plugged in the master cylinder.

[heavyd]

I still have to get the back tire back on to test, it cooked a wheel bearing last weekend, but I think I found the issue. ID10T issue for sure if it's the problem, the little stopper in the bottom of the master cylinder was in upside down. I cleaned out the master which had more gunk than I would have expected for 1 year old fluid, fixed the stopper and bled another mityvac full of fluid, but didn't see any air. I also pulled the lever apart, the bushing looks fine, and cleaned/lubed it.

Would that stopper being upside down cause this sort of issue? It is there to regulate the return right?

Just wondering if the inner seal that keeps the engine / transmission oil out of the slave cylinder is leaking. This would put oil on the back side of the slave cylinder. If this happens maybe the cylinder is trapped between clutch fluid and engine fluid impeding the slave cylinder movement. Seems as though the cylinder would be able to push oil back past the seal or out weep hole, but at what rate? Not enough travel by the slave cylinder?

Still wondering about the metal in the oil issue. Did you have to replace parts that were worn or scored? How was the prior repair done incorrectly that caused it to fail?

Trouble shooting from a distance is poor at best.
Maybe you could get help from some one close by.

I replaced the oil seal behind the slave but I suppose that doesn't mean it can't be leaking. The best I can tell, the metal in the oil came from the clutch steels. All of the steels and friction plates, dampener plate and spring have all been replaced. My best guess is that the plates were not restacked in the correct orientation the first time but foolish me didn't take any pictures before I pulled it apart.