Air in brake hyds - Honda RC51 Forum : RC51 Motorcycle Forums
 1Likes
  • 1 Post By C420sailor
 
LinkBack Thread Tools Display Modes
post #1 of 7 (permalink) Old 02-21-2016, 02:26 PM Thread Starter
Junior Member
 
Join Date: Feb 2014
Location: Virginia Beach, VA
Posts: 22
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Air in brake hyds

Came out to the bike to find a soft lever that goes all the way to the grip. No fluid on the bike/ground. I flushed and bled the system to a beautifully firm lever, and went riding. The bike sat for a couple of weeks and the soft lever is back.

Plan is to rebuild the MC and replace the crush washers in the system. Would you guys rebuild the calipers too, or just the MC?

2004 Honda RC51 - Nicky Hayden Edition
2005 Honda CBR1000RR - Titanium/Black
1983 Honda V65 Magna - Black
2015 Boeing F/A-18E Super Hornet
C420sailor is offline  
Sponsored Links
Advertisement
 
post #2 of 7 (permalink) Old 02-21-2016, 04:47 PM
Senior Member
 
jondog9's Avatar
 
Join Date: Aug 2010
Location: Northern CA
Posts: 8,653
Mentioned: 15 Post(s)
Quoted: 317 Post(s)
You give very little info to decisively answer that. How long have you had the bike, when were the calipers last rebuilt? Last brake fluid flush? How is the brake pad wear? even or uneven?

Start with rebuilding the master.
Inspect the rubber line and clamps from the reservoir to the master.
While you're at it, remove the calipers from the mounts, inspect the pistons in the caliper. Any sign of leaking?
Extend the pistons some, clean with brake cleaner or brake fluid, lube the pistons with clean brake fluid and push them back in. When pushing the pistons back in, crack the bleeder valve so the fluid drains into a container instead of back up the brake line into the master.
If you have OEM rubber brake lines, inspect, and consider replacing them. You'll get better feedback with a set of quality steel braided lines and a double bango bolt at the master.
NAPA has a decent selection of crush washers in bags of 10 for like $8.

Hope that helps.

John, 2000 RC51 #000100

jondog9 is offline  
post #3 of 7 (permalink) Old 02-21-2016, 05:56 PM
Senior Member
 
kwtoxman's Avatar
 
Join Date: Oct 2012
Location: Canada
Posts: 2,146
Mentioned: 11 Post(s)
Quoted: 109 Post(s)
If the caliper seals are leaking it will be visible. It was with mine.

I'd not replace unless visible or no other changes have fixed the problem.
kwtoxman is online now  
 
post #4 of 7 (permalink) Old 02-21-2016, 06:05 PM Thread Starter
Junior Member
 
Join Date: Feb 2014
Location: Virginia Beach, VA
Posts: 22
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by jondog9 View Post
You give very little info to decisively answer that. How long have you had the bike, when were the calipers last rebuilt? Last brake fluid flush? How is the brake pad wear? even or uneven?

Start with rebuilding the master.
Inspect the rubber line and clamps from the reservoir to the master.
While you're at it, remove the calipers from the mounts, inspect the pistons in the caliper. Any sign of leaking?
Extend the pistons some, clean with brake cleaner or brake fluid, lube the pistons with clean brake fluid and push them back in. When pushing the pistons back in, crack the bleeder valve so the fluid drains into a container instead of back up the brake line into the master.
If you have OEM rubber brake lines, inspect, and consider replacing them. You'll get better feedback with a set of quality steel braided lines and a double bango bolt at the master.
NAPA has a decent selection of crush washers in bags of 10 for like $8.

Hope that helps.
The bike is an '04 with ~12,000 miles. I don't think they've ever been rebuilt---I'm not the original owner. I've owned the bike for two years, but I've only been riding it for about nine months.

I flushed and bled the system in October with great results---until the bike sat for a couple of weeks. While doing that, I cleaned and lubed the pins, and replaced the brake pads. The pistons looked good (I cleaned what I could without removing them completely), and the front brakes show no signs of sticking/dragging. The old ones had even wear. It has stock lines.
C420sailor is offline  
post #5 of 7 (permalink) Old 02-24-2016, 10:31 AM
Member
 
Join Date: Sep 2014
Location: Chicago
Posts: 90
Mentioned: 0 Post(s)
Quoted: 9 Post(s)
If the brake lever firms up after pumping it a dozen times or so I would think there is air trapped in the system. Try re bleeding the brakes then pull the brake lever in a little bit and hold it there with either a ty-rap or tape over night. This helps move trapped air into the reservoir
02RC is offline  
post #6 of 7 (permalink) Old 02-24-2016, 11:28 AM
Senior Member
 
Join Date: Feb 2013
Location: Greenwich London
Posts: 717
Mentioned: 4 Post(s)
Quoted: 82 Post(s)
Standard lever?
dansp1 is online now  
post #7 of 7 (permalink) Old 04-10-2016, 10:54 AM Thread Starter
Junior Member
 
Join Date: Feb 2014
Location: Virginia Beach, VA
Posts: 22
Mentioned: 0 Post(s)
Quoted: 0 Post(s)
Follow up.

I rebuilt the MC. I found a hardened deposit of crystallized brake fluid in the bore, which I suspect was chewing up the seals each time they passed over it. Copious amounts of brake cleaner and a little elbow grease removed it, with no bore pitting noted. I installed the new kit, flushed and bled the system, and two weeks later I still have a beautifully firm lever. Hope this helps someone in the future.
Burntclutches likes this.

2004 Honda RC51 - Nicky Hayden Edition
2005 Honda CBR1000RR - Titanium/Black
1983 Honda V65 Magna - Black
2015 Boeing F/A-18E Super Hornet
C420sailor is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Honda RC51 Forum : RC51 Motorcycle Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome