Bike not ridden for a few years, now problems with rear brake and ABS system

[mindtrip]

Been a very long time since I've been on the site; picked up rock climbing and really got into it, built a Sprinter camper van and everything which has sucked up the last 5-6 years. I was still commuting on my 2006 AV (no electric shift) until probably sometime in 2016 or mid 2017, but not at all since then. I did Stabil the fuel, put on a battery tender, etc and would start it periodically and get the engine hot, but no actual riding.

The battery tender I was using died without my realizing and the battery then died, so I pulled it out of storage this week and replaced the battery. I've been going over everything, starts and runs just fine and everything is working properly EXCEPT the rear brake--the pedal now bottoms out completely and the brake generates zero pressure; it will stop a spinning wheel when the clutch is disengage but not stop the wheel spinning if the clutch is engaged and the bike is idling in 1st gear. During the time in storage the bike hasn't leaked any brake fluid and the reservoir is full. In addition the ABS warning light flashes once I engage the clutch and rev the engine up above ~1200 rpm, then turns solid, which indicates some kind of problem with the ABS system. So now I have a couple of questions for anyone in the know:

1) Is there any chance that just changing the brake fluid and bleeding the rear brake could get it working again, or should I not even bother trying and just rebuild the master cylinder?

2) Could the ABS warning light be related to the lack fluid pressure, or is there something really wrong? It does come on even if I don't try to engage the brake which makes me think it's the latter. In that case any ideas what's the most likely culprit and recommended fix? I've done some searching and read some recommendations to flush the fluid in the abs box as well, but limited success with that approach for others having a problem with the abs system.

Thanks for any insights anyone can provide!

EDIT: Ok, I just read that with the bike on the center stand and running the rear wheel, the light will come on as the front wheel isn't moving as well. So I guess for now it's just question 1--should I bite the bullet and order a rear master cylinder rebuild kit, or try flushing and bleeding the rear brake system first? Once I have a functional brake, I'll see what happens to the ABS light.

 

[RossKean]

Fully bleed ALL hydraulics.  Clutch, both front calipers, FRONT LINKED PISTON PAIR (lower bleeder on right caliper), rear caliper.

Remove rear brake pedal and clean/grease pivot.  Do yourself a favor and clean up the shift linkage and pivot while you are at it.

Do the clutch and brake handlebar levers - don't forget to clean/grease the brass bushing on the clutch lever.

I am guessing that the rear brake will come back.  Probably some air in the system.  It would be a very good idea to activate the ABS and let it cycle some fresh fluid through it.  Either on a sandy parking lot or using a jumper and the following:



Probably should read up the info in the Service Manual.

Hopefully the ABS block is OK - Gen II seem to be more robust than the Gen I blocks.  Seal problems aren't common and I would definitely flush fluid and exercise the ABS system before rebuilding the master cylinder (or slave cylinder(s)).

 

[mindtrip]

@RossKean Yep a flush and bleed did the trick. I’d planned on changing all fluids and lubing all pivots and the final drive anyway as it’s been years since any if this was done; relieved this fixed it. Found that ABS maintenance procedure on another site today, exact same one as you linked. I hadn't ever seen that before so the brake fluid had *never* been changed inside the ABS box! Thanks for linking that. MamaYama doesn’t sell that diagnostic tool anymore, but it looked like it was just jumping the top two pins so I used an alligator clip diagnostic electrical wire I had made—worked great, will add this to my regular maintenance. 

Many thanks!

 

[dcarver]

Good job Ross Keen!

 

[Ludwig61]

MamaYama doesn’t sell that diagnostic tool anymore, but it looked like it was just jumping the top two pins so I used an alligator clip diagnostic electrical wire I had made—worked great, will add this to my regular maintenance.

They are being made by someone: https://www.fjrforum.com/topic/175908-fjr-abs-test-harness

 

[mindtrip]

They are being made by someone: https://www.fjrforum.com/topic/175908-fjr-abs-test-harness

Thanks for the link!

Fully bleed ALL hydraulics.  Clutch, both front calipers, FRONT LINKED PISTON PAIR (lower bleeder on right caliper), rear caliper.

I'm hoping someone can help as I have a new problem. The clutch was working 100% before I bled  it. However, it needed a full flush and during that I screwed up and let the reservoir on the handlebar drain completely, so air got into the system. Now, no matter what I do, I can't bleed it enough to get the clutch to work.  I put a mityvac on it and there was a TON of air in the drain line, even with barely opening the nipple, so I removed the nipple and wrapped it with teflon tape. Even then I'm getting a ton of air during every attempt to bleed. So I stopped using the mityvac altogether and just used the squeeze-open-close-release method desribed in the service manual, and after another 8-12 oz of fluid run through the system I’m STILL getting a ton of air with each opening if the bleed nipple. The clutch will not fully disengage so even with the clutch lever pulled in, the wheel wants to spin if the bike is in gear.

Can anyone tell me what I'm doing wrong? I've put a ton of fluid through it and can't get it to bleed off all air.

 

[RossKean]

I haven't had issues bleeding clutch without a vacuum or Speedbleeders - although lots of people like them.  If it is being stubborn, get out what air you can and then use a bungie cord to hold the clutch lever to the grip and leave it overnight.  Sometimes, the little bubbles just need some time to rise to the top.  

You will sometimes get a little wheel spin either in neutral or in gear with the clutch lever pulled.  If it is spinning fast or if it takes a significant amount of force to stop it then it is too much.  Should be able to stop and hold it easily.  If not, there is a real problem with bleeding.

 

[mindtrip]

Thanks for the info. I’m unable to stop it with just my foot against the tire—I’m concerned that’s too much spin. Though the engine doesn’t stall when applying the rear brake it does noticeably bog down, and I think this will prematurely wear the clutch. Thanks for the bungee tip, hadn’t heard that one before. I’ll give it a try!

 

[RossKean]

That is definitely too much wheel spin.  Good luck getting all the bubbles out.

 

[lonerider]

 You might try alternately bleeding at the banjo fitting at the master cylinder and the slave cylinder. Air likes to rise to the highest point and I've found this method to be effective on all four of my bikes with hydraulic clutches. Be careful not to get any fluid on painted surfaces. 

 

[mindtrip]

They are being made by someone: https://www.fjrforum.com/topic/175908-fjr-abs-test-harness

Thanks for the link Ludwig61, just ordered one. Will be handier than having to dig out that connector every time!

@RossKean and @lonerider  Thanks for the advice.  I've put about 36 oz of fluid through it at this point and am STILL getting some air bubbles out each day, but much less and the clutch is performing more normally, I can stop the wheel spin now with my foot and the engine doesn't bog at all when the wheel is stopped.  Lonerider, I don't see anywhere in the clutch and master cylinder diagrams on partzilla.com where there's a slave cylinder; am I missing something? I could try bleeding the banjo bolt at the bottom of the master cylinder reservoir.

 

[lonerider]

Slave cylinder is part# 28. The banjo bolt at the master cylinder is the one I mentioned. When I bleed mine, I wrap a rag around the bolt, pump the lever a half dozen times, and, while holding the lever in, break the bolt loose and re tighten it. Air tends to go to the highest point. This purges the air without trying to pump it down to the bleeder at the slave cylinder.