Launching clutch - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 24 (permalink) Old 03-21-2011, 01:53 PM Thread Starter
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Launching clutch

I rode my RC about 3 or 4 times before I changed my clutch fluid. I'm familiar with the feel of a hydralic clutch from my VFR. Pre-fluid change, the clutch felt normal, except once in a while, within 10 or 15 minutes of startup. In first gear, from a stop, as I ease the clutch out, it'll just launch as it begins to engage. Like I dumped the clutch. That's when you find out how fast your reflexes are, cause I instinctivly squeeze the clutch handle back in with a quickness! It's only done that one time per ride, but not every ride.

After clutch fluid change, (the blue Spectre, is that ok?) it still does that. I'm still working on getting air out, cause I had a spongy clutch, and now it won't disengage at all. And to make matter's worse, this morning when I loosened the banjo bolt (just a tiny bit) to get the air out of that high point at the master, I let go of the handle to quick, something came apart in there. Cause now the handle only depresses halfway then stops dead. Plunger pin is still visable.

to the service manual...
Anyone know if this sounds like one issue, or two unrelated issues, like air bubbles and something else?

John, 2000 RC51 #000100

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post #2 of 24 (permalink) Old 03-22-2011, 08:10 PM
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This sounds like two different issues. No mighty vac available?

Or, you started with one that caused the other.

Let me understand this, when you let go of the handle, the piston to the hand pump is now only pressing in half way?

If it is the hand pump, maybe remove the assy from the handle bar and see if you can get the pump working again. (If its cocked or bent, you may not be able to see it on the bar.)

If you have aftermarket levers, make sure the pivot point is well greased and free of debris.



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post #3 of 24 (permalink) Old 03-23-2011, 12:26 AM Thread Starter
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No mighty vac. Getting one asap.

Let me understand this, when you let go of the handle, the piston to the hand pump is now only pressing in half way?

Yep, exactly.

If it is the hand pump, maybe remove the assy from the handle bar and see if you can get the pump working again. (If its cocked or bent, you may not be able to see it on the bar.)

1 step forward, 2 steps back, huh? Now I cant get to it for a couple days-work. But that's pretty much the plan. I can see the pin as it follows the clutch handle out. And yea, it will only go into the hand pump? halfway. Whatever's causing that could be both problems, maybe.

Not all that familiar with different clutch fluids, but is the Spectro 10 wt. ok? The dealership recommended it. I had the impression the RC was only supposed to use DOT4 brake fluid in the clutch??? After figuring out the pin/handpump issue, I'll bleed the system again, with my new (by then) mighty vac and DOT4.

So after i do that I just have run it a little and see what happen's, huh?

Any tips on the final part of bleeding as far as pumping the handle? The first time I did it just like you would do brakes.

John, 2000 RC51 #000100

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post #4 of 24 (permalink) Old 03-23-2011, 01:28 PM
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You bleed the clutch line exactly as you would for brakes.
And you do need DOT4 brake fluid just as for the brakes.
With the Mity-Vac, no lever squeezing is needed as the pump pulls the fluid from the reservoir. Just mind the reservoir level when bleeding.
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post #5 of 24 (permalink) Old 03-23-2011, 06:00 PM Thread Starter
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Ok, thanks guys. I got rained out this morning, so I snuck out to the garage. I took off the clutch handle, and there was the push pin sitting in the piston boot. The piston is stuck in. Wont come back out. It's all sludged up in there. That's where i'm at right now. I did clean the resevoir real good the first time around, but inside the master cylinder musta been pretty gunky too.

SubSailor, I think i remember you mentioning in a different post to put in a new diaphram too when I reassemble?

John, 2000 RC51 #000100


Last edited by jondog9; 03-23-2011 at 06:58 PM. Reason: correction
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post #6 of 24 (permalink) Old 03-23-2011, 06:53 PM Thread Starter
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Just consulted the service manual and everything is becoming clear to me. Time to go back in the garage and take the master apart and clean...

John, 2000 RC51 #000100

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post #7 of 24 (permalink) Old 03-23-2011, 07:27 PM
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Quote:
Originally Posted by jondog9 View Post
Ok, thanks guys. I got rained out this morning, so I snuck out to the garage. I took off the clutch handle, and there was the push pin sitting in the piston boot. The piston is stuck in. Wont come back out. It's all sludged up in there. That's where i'm at right now. I did clean the resevoir real good the first time around, but inside the master cylinder musta been pretty gunky too.

SubSailor, I think i remember you mentioning in a different post to put in a new diaphram too when I reassemble?
Not exactly. I mentioned that I took my ex-Busa to a local shop to have it serviced and they screwed it up by installing a diaphragm from God knows what bike instead of the proper one.

This diaphragm was much, much larger than the original. And of course did not seal.
So as the bike sat, the fluid sucked up all that humidity here in Florida, and turned into a black goo.

I thought initially the fluid discolored from use, as they often do.
But when I when to flush and bleed last year in preparation of selling it, what I saw was way more than discolored.
It had black slime all inside the reservoir.

Needless to say, I was pissed when I compared diaphragms.
It ain't hard to to do a good job. Just attention to detail.
That's why I always try to do the work myself, if I have the tools to do it.
And gradually I'm obtaining the tools to everything myself.

Last edited by SubSailor; 03-23-2011 at 11:33 PM.
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post #8 of 24 (permalink) Old 03-23-2011, 09:37 PM
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Sounds like your on the right track now. Brake fluid is some nasty shit and doesn't play well with others. This may explain the sludge.

Yeah, I hate to do shit twice but if there is an issue, sometime you have no choice. Taking this equipment off is tedious but as you found out, very critical.

DOT 4 not matter what shop/dealership tell you. Honda doesn't put this in the manual or in a vehicle for no apparent reason.

Like Sub stated, just like the brakes....run the bike for maybe a week then bleed again a few times to get the residual air out of the lines. (Brake fluid when agitated collects hundreds of little air bubbles...)

Be patient and take care.



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post #9 of 24 (permalink) Old 03-23-2011, 11:32 PM Thread Starter
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Some mistakes I only make once. DOT4. Only DOT4. And 10-4 on paint vs. brake fluid.
Thanks for all the help SubSailor and Madbuyer. Really helpful, good stuff.

I got my clutch master all apart. It was a little gooey in there, the master piston cups were all gunked up. And they appear to be distorted a little, hard to tell without comparing them to new. So then I took apart the slave cylinder. The pictures explain. Picture #1: I just can't figure out what critter got in there and took a poop inside the housing. #3 is top inside slave housing. #4 is the bottom inside, See where the tarnish is missing? That's where the poo was sitting

Does anyone know where I can get just the cups and seals I need??? At least for the master. (They sell the slave cup and seal seperate for $12.50) Looks like they want to sell the whole master piston in order to get the 2 cups i need. $45. Same with the master pushrod. I just need the cup, but gotta buy the whole part for $15.

That's assuming these cylinders pass for tollerance. Gonna take them along with the sevrice manual specs to a mechanic buddy that has a digital caliper tomorrow.
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John, 2000 RC51 #000100

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post #10 of 24 (permalink) Old 03-23-2011, 11:45 PM
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Whew that's some nasty looking sludge.
No wonder it's not working right.
Hopefully the slave cylinder and piston aren't worn too badly.
Otherwise it's be best to replace them and the cup if damaged.

Last edited by SubSailor; 03-23-2011 at 11:49 PM.
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