Nighthawk-Forums.com - Your Honda Nighthawk Motorcycle Forum !
April 21, 2014, 01:04:27 AM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
News: hot See the "Forum News" section for an important announcement!  hot
 
   Home   Help Search Member Map Contact Login Register  

Pages: [1]   Go Down
  Print  
Author Topic: Bleeding the clutch...  (Read 3596 times)
0 Members and 1 Guest are viewing this topic.
biometrics Topic starter
Contributing Member
***
Offline Offline

Gender: Male
Age: 66
Location: Winchester, VA
Bike: 1983 Nighthawk CB650SC
Posts: 212

Join Date: Oct, 2009


Kagnew Station (Eritrea) 1972-1973


WWW

Ignore
« on: October 03, 2010, 07:57:59 AM »

Last weekend after returning from a 100 mile bike ride, I parked the NH at the end of the driveway because I thought I would have to run out on an errand later, but as it turned out the errand was unnecessary.

When it got to be bedtime, the weather report predicting rain overnight made me remember that I had not garaged the bike and went out to ride it the 60 feet from the  street to the garage and started the bike as ususal. 

NO CLUTCH response! 
I couldn't shift the bike from neutral to first without killing the engine, and couldn't restart it in gear with the clutch depressed!  What ever the problem, I was glad it didn't happen in the middle of the 100 mile ride.

So, the NH sat unused all week and I drove the van to work.  Yesterday afternoon, I decided I better get diagnosing what was wrong while it was still daylight if there were any chance of riding the bike this week before the cold weather starts to set in...  So I went to the garage and put the bike on its center stand, covered the gas tank with plastic to protect it from any brake fluid that might stray from where I needed it, and removed the cover on the clutch master cylinder reservoir... It was empty!   yikes   I checked the sight glass in the front and it still looked like it had fluid, but that turned out to be a dirty sight glass window!  banghead  SO I was sure I had air in the system.  Cry

I decided that since the master cylinder had sludge in the bottom, that my best bet was to remove it from the bike and disassemble it to make sure it didn't also need to be rebuilt.  My search of the forum gave me the confidence to attempt to do this... something I have never done before.  The only tools necessary are the right size socket head allen wrench (8mm) and something you can live without but I am so glad I had picked one up a couple years ago at a parking lot sale:  A since cheap chinese set of snap ring or circlip pliers.  You may be able to get that snap ring out that holds in the piston without a set of these BUT I DON"T RECOMMEND IT!

There are plenty of threads give the specifics on disasembly and bleeding.  A few minutes later, using DAWN grease-cutting dish washing liquid soap and really hot water, I had the MC apart, and tooth brushed the sludge out to find that the cylinder was not scored from the sludge.  My digital micrometer verified that the piston was still within specifications, and the rubber piston components looked good.  Some compressed air removed any trace of moisture from the assemblies and it was time to put it back together.

I had an old bottle of DOT 3 fluid that I used to coat all components before assembly, but I had a new bottle of DOT 4 brake fluid that I had purchased right after I got the NH because that is what is specified on the top of both the clutch and brake master cylinders lids.

Once on the handlebars, I put my thumb loosely over the opening where the banjo bolt attaches the brake line to the MC and covered that hand with a rag, and slowly pumped the MC once.  Air and fluid came out, and I then sealed the hole with my thumb and released the lever slowly.  I repeated this three times and then refilled the reservoir.

Then I reattached the brake line loosely to the MC, and repeated the procedure (also covered the fitting with a rag to catch any fluid spillage). After what appeared to be three successive squirts from the loosely attached fitting, I tightened the connection confident that I had removed most of the air from the system.  I refilled the reservoir one more time and then slowly tested the lever and I had "some" resistance... so I knew I was making progress!  happy1

Then I found an 8mm box end wrench and carefully loosened the bleeder screw on the slave cylinder.  If I had more time I would have removed the slave cylinder and cleaned it as well, but I didn't have much time so I decided to just bleed it and see what the results were.  I took the clear plastic hose (6') that I had purchased weeks before because I saw it on sale, and attached it to the slightly loosened bleeder screw and watched carefully as I sucked the other end.  About 6 inches of dark fluid filled the hose followed by fluid that was getting cleaner!

I followed standard bleeding procedure and closed the fitting and dumped the brake fluid I had removed into my waste oil container.  I repeated this process three times, while carefully watching both the hose and the reservoir until I was getting no bubbles, and then tightened the fitting.

I carefully squeezed the lever and TA DA!  I had what felt like good clutch resistance!  Three dollars worth of hose, and four dollars worth of new fluid and an hour of my time and I could ride my bike again!  wings  What a great feeling not to have to take my bike somewhere else and have some moron charge me a bundle of money to MAYBE fix my bike. 

Next challenge will be the BRAKE master cylinder!  Whne the riding season is completely over... in the mean time, I made SURE that the brake MC has a full load of fluid!

BTW, I am sorry there are no photos, but with my hands wet with brake fluid at different times, I didn't think it was a good idea to be handling my $400 camera...  maybe on the next repair.

Thaks to all who contribute to this forum.  I hope my description of this process helps somebody else keep their bike safely on the road.

Happy Trails to YOU!   thumb



Logged

__________
regards, -JS
1983 Nighthawk CB650SC (SOLD!)
SliverXZennon
Dedicated Member
****
Offline Offline

Gender: Male
Age: 30
Location: Wadsworth, Ohio
Bike: 1996 Honda Magna 750
Posts: 560

Join Date: Aug, 2009





Ignore
« Reply #1 on: October 03, 2010, 08:35:26 AM »

Wow, I was thinking this was going to turn out like mine... WHEW I'm glad it didn't. Congrats on the bleeding, it can be a royal pain...  biker_h4h1
Logged

700 'Hawk - Sold..
Hangster
Guest

« Reply #2 on: October 03, 2010, 10:01:46 AM »

Congrats , feels good not to have to rely on someone else and spend crazy money  super
Logged
happycommuter
--- NHF---
*
Offline Offline

Gender: Male
Age: 40
Location: Jersey
Bike: '91 EX500
Posts: 3605

Join Date: Mar, 2008



WWW

Ignore
« Reply #3 on: October 04, 2010, 04:46:09 AM »

Next challenge will be the BRAKE master cylinder!
Yup, the hydraulics are best done together.  And if the DPO neglected one...

After fork oil, the most neglected fluid.  Really needs new fluid every couple years due to the hydrophilic nature.
Logged

Soupskin
--- NHF---
*
Offline Offline

Location: Atlanta, GA
Bike: '91 Honda CB750, '12 Ninja 1000 ABS
Posts: 4575

Join Date: Mar, 2009


They see me rollin'




Ignore
« Reply #4 on: October 04, 2010, 05:16:49 AM »

Nice job!

When you do your brakes, plan on taking your calipers apart to clean them out thoroughly as well.  I was amazed at the sludge and rust I found in mine.
Logged
biometrics Topic starter
Contributing Member
***
Offline Offline

Gender: Male
Age: 66
Location: Winchester, VA
Bike: 1983 Nighthawk CB650SC
Posts: 212

Join Date: Oct, 2009


Kagnew Station (Eritrea) 1972-1973


WWW

Ignore
« Reply #5 on: October 04, 2010, 05:59:16 AM »

I plan to go back and do the slave cylinder as well during the cold wet off season in a few weeks.  I was just concerned that if I took the slave cylinder apart, it might deadline the bike until I had a chance to rebuild it.  The calipers will definitely be part of the brake system service--- complete disassembly cleaning and restore/replace as necessary.  I have done automotive brakes many times and familiar with the work, I had just never worked on a hydraulic clutch before so I was a little apprehensive... That won't be a problem in the future.   thumb  biker_h4h1
Logged

__________
regards, -JS
1983 Nighthawk CB650SC (SOLD!)
SirSeanSean
The Brown Knight.
--- NHF---
*
Offline Offline

Gender: Male
Age: 22
Location: Lynchburg, Virginia
Bike: 1984 CB650SC (Sold) 1995 750(Sold) CM200 (Sold).
Posts: 2088

Join Date: May, 2010


Drink Coffee.




Ignore
« Reply #6 on: October 04, 2010, 06:09:33 AM »

Glad it all went well with you. I just bled my brakes yesterday. New experience for me.  knary I plan to bleed the clutch soon as well. I was trying to find the bleeder screw for it, but couldn't find it. Although I do have a clymer manual coming in the mail soon. Once that happens I'll rebuild my calipers as well. This is what my brake fluid looked like as I was bleeding them.


Logged
biometrics Topic starter
Contributing Member
***
Offline Offline

Gender: Male
Age: 66
Location: Winchester, VA
Bike: 1983 Nighthawk CB650SC
Posts: 212

Join Date: Oct, 2009


Kagnew Station (Eritrea) 1972-1973


WWW

Ignore
« Reply #7 on: October 04, 2010, 06:14:11 AM »

You have to remove the plastic cover near your left footpeg to gain access to the clutch slave cylinder and bleeding screw.  The cover is held in place with similar mounting pegs like the upper side covers. Just make sure you have plenty of light, and can see what you are doing so you don't have to force anything and break off one of the retaining pegs.  You will have to PULL but I didn't have a problem... hopefully you won't either.  

I didn't have a photo of what the clutch fluid looked like because THERE WASN'T ANY! yikes I won't ever let that happen again!
Logged

__________
regards, -JS
1983 Nighthawk CB650SC (SOLD!)
SirSeanSean
The Brown Knight.
--- NHF---
*
Offline Offline

Gender: Male
Age: 22
Location: Lynchburg, Virginia
Bike: 1984 CB650SC (Sold) 1995 750(Sold) CM200 (Sold).
Posts: 2088

Join Date: May, 2010


Drink Coffee.




Ignore
« Reply #8 on: October 12, 2010, 11:34:38 AM »

Thanks! I was able to find it and now I have fresh new oil in the clutch lines.
Logged
drdubb
--- NHF---
*
Offline Offline

Gender: Male
Age: 60
Location: Raleigh, North Carolina
Bike: '95 750 Nighthawk, '83 650SC Nighthawk, '71 SL350K1, '06 DR650
Posts: 5060

Join Date: Dec, 2009


OFWG


WWW

Ignore
« Reply #9 on: October 12, 2010, 05:10:49 PM »

Makes me want to go out and bleed mine. (on the other hand, I may wait till it gets too cold to ride)
Logged

Dance as if no one is looking.
OnlyatNight
New Member
*
Offline Offline

Bike: 85 Nighthawk 650
Posts: 22

Join Date: May, 2012




Ignore
« Reply #10 on: May 07, 2012, 01:26:36 PM »

The top of this page warns me that this is an old topic...but I still think it might be easier than starting a new topic.  I picked up a 650 a little over a week ago. It had been wrecked and left outside for a couple years.  I finally got it running good today but when I tried to put it into gear it lurched forward and died.  I opened up the left side reservoir on the handlebars because I think it's for my clutch.  It was totally empty.  I'd like to refill it and bleed the lines but I'm not sure how to do so. I don't have a shop manual.  I think I have the general idea, that is, find the bleed screw and open that.  Squeeze the clutch lever, open the top and pour clean dot 3 or 4 brake fluid in, release the lever and start suction on bottom end by the bleed screw?  If that's correct could someone post a picture or tell me how to find the bleed screw?

I got the bike for 300 dollars and before a week ago I had zero experience working on anything other than my homework.  So far In everything I've done I've just gone slow and done my best not to break anything.
Logged
happycommuter
--- NHF---
*
Offline Offline

Gender: Male
Age: 40
Location: Jersey
Bike: '91 EX500
Posts: 3605

Join Date: Mar, 2008



WWW

Ignore
« Reply #11 on: May 07, 2012, 05:41:37 PM »

The bleed nipple is exactly like the one on the brake caliper.  It should have a little black rubber cap/cover and is loosened with an 8mm hex.  I'd say the clutch slave cylinder is maybe half-dollar sized in diameter and is connected to brake lines.

If you don't have a vacuum/pressure bleeder, you'll need to pump the lever with the bleed nipple closed to develop pressure (lever should feel firmer) so air gets expelled when nipple is opened.  For fill/flush, you can totally pump the lever to push fluid through, just keep the reservoir full enough not to suck in air.  Otherwise it's pump lever, hold lever, open nipple, close nipple, repeat.
Logged

skramer360
--- NHF---
*
Offline Offline

Gender: Male
Age: 45
Location: Bloomington, In
Bike: 1985 cb700sc. The "s"
Posts: 2316

Join Date: Aug, 2008


Is 46




Ignore
« Reply #12 on: May 07, 2012, 07:48:07 PM »

When I replaced the sight glass on both my Master Cylinders this past winter, I followed my usual M.O. for bleeding. I opened the bleeder screw and put a cup under it. Then I filled the reservoir and waited. I kept the reservoir full and waited for the fluid to come out a stream from the bleeder. After that I did the usual pull the lever and then open the bleeder for just a couple of cycles. Done. Gravity worked and I had no frustration trying to get the air out.
Logged

I'd rather be riding my blue '85 (700s)
  Steve
Pages: [1]   Go Up
  Print  
 
Jump to:  

Copyright© 2008 - 2013 Nighthawk-Forums.com
All Rights Reserved
Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2013, Simple Machines | Sitemap Valid XHTML 1.0! Valid CSS!