Clutch slipped then went back to normal

[Vfrider1]

OK group, I have searched the boards extensively and have not come up with a good train of thought on my current clutch problem.

Bear with me while give some back ground on the bike:

I purchased the bike used with 30k on the clock. I had the dead clutch lever and replaced the slave cylinder. Things still did not feel right so I went ahead and rebuilt the master cylinder as well. For the last two weeks and about 500 miles everything has been peachy and I was patting myself on the back for a job well done.... 

Until today... 

On the way back from lunch I had a 80 MPH run on the free way, about 20 minutes or so...temps in the upper 90's. pulled off the free way to get gas, after fill up and restart I pull out and rev the engine a little higher than normal. I'm thinking bad form on my part and continue on my way.

At the next light I let the clutch out and the revs are all over the place... I realize things are not as they should be and go into "get home mode".

I baby things in order not to make matters worse and burn up the clutch. I have it in the back of my mind that the clutch master is not releasing fully. Just getting the bike up the slight incline into the garage is dicey at best.

I went ahead and bled the system again, I did not notice any air release. I did however notice a small fleck of what I think was black paint in the fluid reservoir.    problem sorted? Did this clog up the return flow to the master cylinder?

After the bleed I took the bike out for a road test and all is right with the world again... 

Clutch engagement is rock solid without a hint of slippage even under HARD acceleration...

I have some long weekend rides planned and I want to have confidence in the bike again, any suggestions or ops checks that I could perform to firm up my own diagnosis?

If you have read this far THANKS! 

John

[Son of Pappy]

My bet is someone added the wrong oil.  Seriously.  Energy conserving type will cause the clutch to slip.  Before you replace the clutch fibers I would do a good engine flush and use appropriate oil, worth a try.

[Vfrider1]

silverdammit,

I had the same thought as well. When I purchased the bike I did change the oil with a motorcycle specific oil, (Mobile 1 MX4T I think) would a contaminated clutch have this intermittent failure? I did notice the oil in the level gauge was slightly foamed immediately after I shut it off after the clutch slipping incident. Perhaps another oil change would be a good idea? I currently have about 2000 miles on this oil change.

Thanks

John

[Son of Pappy]

I'd try the flush just to rule it out.  I had similar issues, but it turned out the Hippo Hands were collapsing under heavy acceleration

[Vfrider1]

Thanks Silverdammit,

One question, when you say "flush" do you mean to use an engine flush, the kind that can be found at the local parts store?

John

[Son of Pappy]

Yup, engine flush, something to remove the additives off the fibers.  As I do as much clutch work as anyone I know and I have 54,000 miles on a souped up engine I have a hard time believing your clutch is toast, possible yes, but clutch wear just hasn't been an issue that I have heard or read about.

[B.D.F.]

The hydraulics on these bikes are a horror show to bleed and even worse to bleed fully. I think what happened to you was an air bubble in the clutch hydraulics expanded and uncoupled the clutch a little bit. The last bleeding again got the system working but going by my own and other's histories with these bikes, you may well not yet have a clean clutch hydraulic system. Do a search on brake bleeding and you will find a lot of methods such as using a rubber band on the brake lever overnight and such- it is the effort to get the last few spots of air out of the system. Once fully bled, they work wonderfully (brake and clutch) for a long time but the clutch system seems to need the occasional bleed over the course of time, like once every year or so.

Power bleeding these systems is the way to go- either a powered pressure system or a vacuum system. Once that is done my guess is that you will notice that the clutch is crisper and more precise as well as repeatable both hot and cold as compared to how it was before.

I ended up buying an air- powered hydraulic bleeding system from Mity Vac: not the hand operated type (I tried two of those without success) but the continuous type. Fairly expensive but it makes a very frustrating and nearly (always in my case) impossible job a breeze. It still takes a lot of brake fluid to fully bleed either system but at least using the power unit it is fast and easy.

You might find someone or some shop with a power bleeder and hire them to bleed your system. Once you have a power bleeder and have the master cylinder open, it is only about 5-6 minutes worth of work and so should be reasonable in cost.

As far as the motor oil goes- perhaps but I do not think so. The part of motor oil that causes wet clutches to fail is moly lube or MOS2, molydisulfide, which coats the clutch plates and prevents them from grabbing. Once so glazed, the clutch plates won't work correctly again until they are replaced; no amount of clutch bleeding or adjusting of any kind will 'fix' a clutch that has been slipping due to contact lubricants.

Brian

OK group, I have searched the boards extensively and have not come up with a good train of thought on my current clutch problem.

Bear with me while give some back ground on the bike:

I purchased the bike used with 30k on the clock. I had the dead clutch lever and replaced the slave cylinder. Things still did not feel right so I went ahead and rebuilt the master cylinder as well. For the last two weeks and about 500 miles everything has been peachy and I was patting myself on the back for a job well done.... 

Until today... 

On the way back from lunch I had a 80 MPH run on the free way, about 20 minutes or so...temps in the upper 90's. pulled off the free way to get gas, after fill up and restart I pull out and rev the engine a little higher than normal. I'm thinking bad form on my part and continue on my way.

At the next light I let the clutch out and the revs are all over the place... I realize things are not as they should be and go into "get home mode".

I baby things in order not to make matters worse and burn up the clutch. I have it in the back of my mind that the clutch master is not releasing fully. Just getting the bike up the slight incline into the garage is dicey at best.

I went ahead and bled the system again, I did not notice any air release. I did however notice a small fleck of what I think was black paint in the fluid reservoir.    problem sorted? Did this clog up the return flow to the master cylinder?

After the bleed I took the bike out for a road test and all is right with the world again... 

Clutch engagement is rock solid without a hint of slippage even under HARD acceleration...

I have some long weekend rides planned and I want to have confidence in the bike again, any suggestions or ops checks that I could perform to firm up my own diagnosis?

If you have read this far THANKS! 

John

[Vfrider1]

Thanks for the replies all,

I will take a shot gun approach to this and change the oil and bleed the crap out of the system. (Yay! I get to buy a new tool!  ) " But honey, BDF on the internet said so. It's his fault..."

Regards

John

[gPink]

What altitude are you at? Just wondering.

[Vfrider1]

One mile high here in Denver

John

[gPink]

The reason I ask is I've had brakes go soft in higher altitudes and harden up again as I descended.

[B.D.F.]

Fixed it up for ya' a little bit. I really could do more with this statement but then a mod. would have to come along and delete it. You know, things like- if you descend below sea level does it get 'too hard'? In an airplane it must be soft as butter and just won't work at all? And stuff like that but I won't say it. Nope, wouldn't be prudent....

Brian

The reason I ask is I've had brakes go soft in higher altitudes and harden up (easy boys!) again as I descended.

[VirginiaJim]

Harumph!

[Vfrider1]

Well I have sorted out the problem with my clutch...the plunger from the master cylinder was not seated fully in the clutch lever. It would not allow the plunger to release all the way! I can assume I did not ensure it was assembled properly when I rebuilt it earlier. 
Rule #1 when you have a problem...undo what you just did!

Thanks for all the replies and suggestions

John

[Son of Pappy]

Great news!!  Thanks for the update

[B.D.F.]

Thanks for the final reveal on that.

You do realize that this cuts down your chances of ever going into the C-14 clutch master cylinder rebuild business though, right?

 

Brian

Well I have sorted out the problem with my clutch...the plunger from the master cylinder was not seated fully in the clutch lever. It would not allow the plunger to release all the way! I can assume I did not ensure it was assembled properly when I rebuilt it earlier. 
Rule #1 when you have a problem...undo what you just did!

Thanks for all the replies and suggestions

John

[Vfrider1]

To late ... Already did that 

John