Never-been-serviced brake maintenance? - Kawasaki KLR 650 Forum
2008+ KLR650 Wrenching & Mod Questions For repair, maintaining or modifying discussions related to the newly updated 2008 and beyond, Generation 2 KLR650 Motorcycle.

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post #1 of 11 Old 07-28-2019, 08:48 PM Thread Starter
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Join Date: Aug 2018
Location: Moscow, ID
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Never-been-serviced brake maintenance?

Background: I've never really serviced the KLR's brake calipers, aside from replacing the pads on my old model. My current bike is a 2013 with over 20,000 miles on it, and brake maintenance has been basically non-existent—out of sight, out of mind. I say this to my shame, but hope you'll have pity on me anyway.

My rear brake was making a weird, light humming noise when turned the wheel, so I took a look at it when I had the wheel off for a different reason. The bike has over 20,000 miles and the pads have *never* been replaced, and still have over a 1/4 in of material on it (no typos there). I engine brake a lot, but this seemed very strange. Then I realized that I couldn't budge the caliper pistons. After reefing on it them with a C-clamp, I could budge them a very little. I've not noticed any lack of stopping power from the rear brake, realizing that the rear brake is rather lacking to begin with.

I am assuming this will take plenty of service to get it back in working condition, but I don't know where to start. I've usually found the Clymer to be helpful, but I am still confused. Anyone able to help me out? Please ask questions if anything's unclear. Thanks!
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post #2 of 11 Old 07-30-2019, 07:43 PM
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I don't think it will take that much work... provided your caliper is still good.

I assume that you are familiar with how to bleed the brake system? If so, start there. Continually bleed each system (adding fresh fluid to the reservoir as needed) until the fluid runs clear. Make sure you take the calipers off and compress them to remove any fluid that's hiding there.

After the fluid runs clear and you mount the calipers, you'll need to pump the master cylinder (adding fresh fluid to the reservoir as needed) until the pads seat on the brake disc.

As fate would have it, I just did this to my bike yesterday. I have a 2005 that I've neglected for the last 6-7 years. This year I decided to bring it back to life and do some upgrades. One of them was SS brake lines because the brakes were weak and spongy. I couldn't believe the state of the fluid that came out. It was yellow and cloudy and the front master cylinder has something like rust in it. I'm going to guess that part of the problem was just the brake fluid. I flushed both systems and finally have proper brakes.
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post #3 of 11 Old 07-30-2019, 08:38 PM
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brycelyoung,
If the reservoir has been re-filled there may Not be enough space to back-compress the caliper piston Volume back into the reservoir.

I'll suggest to release the bleeder valve and compress the pistons back into the caliper (close the valve), then pump the lever to Re-extend the slave pistons.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 84,000+ miles & counting
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post #4 of 11 Old 07-30-2019, 11:18 PM Thread Starter
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Originally Posted by pdwestman View Post
brycelyoung,
If the reservoir has been re-filled there may Not be enough space to back-compress the caliper piston Volume back into the reservoir.

I'll suggest to release the bleeder valve and compress the pistons back into the caliper (close the valve), then pump the lever to Re-extend the slave pistons.
Thanks, PD. So as I was messing around trying to see if the pistons were really stuck, I clamped one of the pistons and pumped the brake a couple times. The other piston did move, but of course, too far, and it came out of the bore completely. I scrambled to clean up the spilled brake fluid, but now I'm wondering if that messes anything with the brake bleeding/fluid changing process? I have read through the brake bleeding section in the manual, but have never performed the service before, so I get to try something new!

Can I take both the pistons out to clean everything out, then put it all back together and bleed and refill the brakes like normal? Any value in the "brake caliper rebuild kit" for around $20?
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post #5 of 11 Old 07-31-2019, 08:02 AM
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Removing the pistons and cleaning everything is probably a good idea at this point. The $20 seal kit may or may not be necessary, pending the condition of your existing seals, but I would probably buy it. Also if it were me, I would remove the existing seals to ensure that their seal groove is scrupulously clean. Crude can build up in that groove and force the seal radially against the piston, which may prevent the piston from retracting fully. Be careful when removing the seals so as to not scratch the groove or bore.

After cleaning the pistons and bores, install the seals and smear some brake fluid in the bores, seals, and pistons before assembling them.

After bleeding the air out of the brake system as much as possible using the bleeder valve, put a weight on the brake pedal to fully depress the master cylinder and maintain this configuration over night. This last step magically removes any remaining air in the hydraulic system. Remove the weight the next morning and pump the brake pedal several times and you will be good to go.

Jason

P.S. There is a rear brake bleeding video in the "How-to..." section of this forum.
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Last edited by Norton 850; 07-31-2019 at 09:30 AM.
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post #6 of 11 Old 07-31-2019, 11:09 AM Thread Starter
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Quote:
Originally Posted by Norton 850 View Post
P.S. There is a rear brake bleeding video in the "How-to..." section of this forum.
Thanks for the tip, I did not know this!
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post #7 of 11 Old 07-31-2019, 11:48 AM Thread Starter
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Do you have a link to that thread, Norton (or anyone)?
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post #8 of 11 Old 07-31-2019, 11:50 AM
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Quote:
Originally Posted by brycelyoung View Post
Do you have a link to that thread, Norton (or anyone)?

Here you go. https://www.klrforum.com/how-tos-tec...placement.html
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post #9 of 11 Old 08-01-2019, 01:01 PM Thread Starter
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One further question: if I remove the pistons from the bores to clean everything as best I can, is it better to just drain the fluid completely? Wouldn’t fluid keep coming out of the caliper otherwise? Or would that only result from pressure being applied? It definitely seems easiest to just bleed and change the fluid without draining it, but if that would introduce air anyway at the caliper by removing the pistons, it would seem more tidy to just drain the fluid and maybe remove the caliper completely, then fill with fluid again after it’s all put back together.
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post #10 of 11 Old 08-01-2019, 01:56 PM
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Chances are high that all of the fluid has already drained out when you accidentally purged the 1st piston out.

Use only fresh DOT 3 or 4 to clean the interior of the assembled brake reservoir. I use a pocket screwdriver to scrub any scum off of the interior of the reservoir & suck the now scummy fluid out with a little squeeze bulb from a medical lab.

pdwestman
Modify at "YOUR OWN RISK"!

Still riding my 1987 KL650-A1. 84,000+ miles & counting
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