2015 C650GT brake flush/fill concern

[Final.Drive]

A friend and I took on a brake flush the other day on my new to me '15 GT. I've done plenty of flushes on various other bikes/brands before and checked the procedure on the new scoot in the service manual. Everything seemed to be pretty standard issue and basic. The problem comes in when my friend inadvertently attached our drain line to the larger bleed valve on the left side of the bike. I pumped the right lever and he cracked open the valve nut. It flushed fine from my perspective at the lever. He didn't notice what he had done until we got around to the right side bleeder and that side looked different. We then discovered the smaller bleeder valve on the left side that looks identical to the right.

We continued to bleed and flush the system and topped off with fresh DOT 4. We thought everything was good but a subsequent ride now indicates a spongy feel at the front lever. We flushed everything well enough that there weren't any air bubbles but now I am wondering about that larger bleeder getting used. The parts fiche's don't call it out specifically and the right side just has a banjo bolt there. Picture included to clarify. It's the larger/lower capped bleeder that I am referring to.

Thoughts about how to regain my firm lever feel and whether it is related to cracking open that wrong bleeder?

 

[motomanjim]

A friend and I took on a brake flush the other day on my new to me '15 GT. I've done plenty of flushes on various other bikes/brands before and checked the procedure on the new scoot in the service manual. Everything seemed to be pretty standard issue and basic. The problem comes in when my friend inadvertently attached our drain line to the larger bleed valve on the left side of the bike. I pumped the right lever and he cracked open the valve nut. It flushed fine from my perspective at the lever. He didn't notice what he had done until we got around to the right side bleeder and that side looked different. We then discovered the smaller bleeder valve on the left side that looks identical to the right.

We continued to bleed and flush the system and topped off with fresh DOT 4. We thought everything was good but a subsequent ride now indicates a spongy feel at the front lever. We flushed everything well enough that there weren't any air bubbles but now I am wondering about that larger bleeder getting used. The parts fiche's don't call it out specifically and the right side just has a banjo bolt there. Picture included to clarify. It's the larger/lower capped bleeder that I am referring to.

Thoughts about how to regain my firm lever feel and whether it is related to cracking open that wrong bleeder?

So if I’m understanding what happened, the drain line was attached to the banjo fitting where the brake line runs from the master cylinder and was bled there. And when it was realized that this happened, did you transfer the drain line to the bleed screw nipple and bleed the caliper from there? I’m showing my ignorance here for I didn’t know this was possible but there are apparently situations where the proper bleed screw is damaged on a caliper and the banjo fitting is used. From a google search, I found a YouTube video in which the poster said the caliper could be removed and in order to be successful, would have to be held vertical as the air inside rises in order for the system to be bled. If I were in this situation, I would go back and bleed the front brakes again concentrating on the left caliper. This may require some extra effort. Here again, I’m just a DIYer who doesn’t know any better but I’m throwing this out anyway. I’m interested in knowing how this turns out.

 

[motomanjim]

In taking a closer look at the front brakes on my 2013 C650GT, the left caliper banjo connection has the bleed screw as shown in your picture. And on the right side caliper, the banjo connection is made with a bolt and no bleed screw. So long story short, I can see how the banjo bleed screw could be selected to drain the brake fluid and overlook the other bleed screw. And just another thought, removing the pads and forcing the pistons back in to the cylinders might help to displace the air. Blocks would then be required to keep the pistons from moving back in position when the brake lever is applied during the bleed process. Before doing this, make sure there’s room in the reservoir to handle the fluid that’s being pushed back in. Hopefully the more knowledgeable members will chime in here.

 

[Final.Drive]

So if I’m understanding what happened, the drain line was attached to the banjo fitting where the brake line runs from the master cylinder and was bled there. And when it was realized that this happened, did you transfer the drain line to the bleed screw nipple and bleed the caliper from there? I’m showing my ignorance here for I didn’t know this was possible but there are apparently situations where the proper bleed screw is damaged on a caliper and the banjo fitting is used. From a google search, I found a YouTube video in which the poster said the caliper could be removed and in order to be successful, would have to be held vertical as the air inside rises in order for the system to be bled. If I were in this situation, I would go back and bleed the front brakes again concentrating on the left caliper. This may require some extra effort. Here again, I’m just a DIYer who doesn’t know any better but I’m throwing this out anyway. I’m interested in knowing how this turns out.

Can you post the link to that YouTube video please?

Yes...we did also go back and connect to the proper smaller bleed valve afterward and continue the process. I'm planning to go back and try that left side again.

 

[motomanjim]

Hope this helps

 

[Final.Drive]

Thanks, Jim. We just went back over that left side and got air bubbles out of both bleeders. Once I have oil back in the bike I will go for another spin to confirm if this firmed up the lever feel. I think we got it.

 

[motomanjim]

Thanks, Jim. We just went back over that left side and got air bubbles out of both bleeders. Once I have oil back in the bike I will go for another spin to confirm if this firmed up the lever feel. I think we got it.

That’s fantastic!