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Brake Issues on a 2009 950.. your thoughts>

16 posts from 10 voices
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  1. Frokkj

    Last spring I had my original levers (brake and clutch) replaced with some nice longer Kury Levers. This was put on at a rally by the people at Kury. I noticed they were wobbly on both my wifes and mine. We went back and the guy made an insert.
    That worked fine for a few months, but by fall, noticed they were somewhat wobbly again and wife had found the metal inserts that were in the original levers, so we took them with us, had them remove the Kury levers, install the metal washer type inserts and the wobble was gone.
    But when I picked up my bike, I noticed that my front brake was very hard. Kury installer said probably got some air in the line. We bled them, they were ok. My wife noticed the same thing. Bled hers, it was ok.
    Sat up for most of winter. Checked my bike and the brakes were hard again and attempting to lock up. Took it to the dealership and they stated that I needed the brake pads changed and brake fluid changed. They did that, then after test riding, it locked up on them at the dealership. The had to put a master cylinder kit on the front. My bike has about 20,000 miles and is 4 years old, so some of that could be expected.. but maybe not the locking up part.
    Wifes sat for the winter, her brakes seemed hard too, when she took it out 3 weeks ago. But not too bad. Took it out Saturday, the brakes were really hard. She squeezed the front several times really hard, to work out whatever was going on and seemed ok. Took off, the bike seemed sluggish. seemed the more the throttle was given the more she was losing power. She shifted down, never touching the brakes. But began to smell something coming from the back of her bike. Worried, she slowed down more and shifted down one more gear. Right as she was about to pull over, probably going about 30 miles an hour, she just barely pulled on the front brake and the applied some pressure to the back brake and she immediately went down and both front and back were locked solid.
    She went down hard and when we attempted with help to get the bike out of the road, it would not roll at all. It was still locked. After about 10 minutes, it finally would roll and took off to take it home. Nursing it slowly, rode the edge of the road, in case this happened again. And sure enough it did. Brakes locked up. Her bike is a 2009, 4000 miles and should not be doing this.
    Neither one of us seemed to have this issue until we had the levers worked on the 2nd time. The first time, with the make shift insert to take up space was Ok.
    Any ideas of what may be going on and what may be happening.. I am at a loss and she is she.

    Thanks, Linda and Jay

  2. yhoower

    Although I can't imagine why a lever change would cause the problem, it sounds to me like the rear brake has a problem too and the lever change wouldn't be involved with that.

    You said you bled the brakes did you replace the brake fluid? Did you double check that you were using the correct brake fluid? (no insult intended)

  3. 9Sdarz

    There is a small Phillips head set screw on the brake lever that is probably adjusted "IN" too far. It is putting pressure on the master cylinder plunger. When you move the brake lever back and forth there should be just a tiny amount of play between the the end of the set screw and plunger on the master cylinder. Loosen the jam nut and move the set screw back just a tiny amount and test. This exact same thing happened to a friend and thats what it was after new levers were installed.

  4. Frokkj

    Thanks Everyone. I didn't change the brake fluid as I didn't think it would need to be changed with just a lever change. But my husband did get his changed and it still happened to him.

    9Sdarz, is this set screw you are talking about underneath the lever? I see there is an allen screw on top of the lever, but it doesn't have a nut on it. Then underneath on the front side of the lever there is a phillips head screw with a nut, if I remember what I saw last night when I looked at it.

    The friend you spole about above, did his lock up or just get tight. That was the worst thing ever and the least expected. Maybe that is why I didn't get hurt as badly as I could have been because I wasn't expecting it, so I didn't tense up. At least the bike didn't get hurt and the crash bars did what they were supposed to do.

    Any anyone that doesn't have crash bars around their back hard bags, I would HIGHLY advocate it. That saved my bags from being eaten up by the pavement!!

    13 STars, please let me know on my questions above and thanks everyone for your input.


  5. freezbirid

    i would say 13 stars is spot on with his answer,the adjusting screw is where the lever touches the master cylinder piston,you MUST have free play there or your brake will rub slightly and get hot,the hotter it gets the more it binds until your wheel locks up,cant believe they didnt check it when they installed the levers,anyone with basic machanical skills should no this. Take Care John

  6. yhoower

    I can accept that 13 is probably right about the front brake.

    What about the rear? Something is causing pressure to build up in the line even thought the master cylinder is not being engaged.

  7. Bikerider50

    My husband's rear brakes has locked up about 3 times causing him to go down once. His bike only has 1800 miles. Think possibly, the back line is a rubber line and goes down the right side of the frame. Maybe the heat from the engine and transmission making the fluid heat up and expand. He is planning to switch to stainless steel lines and change fluid, etc.

  8. 9Sdarz

    The phillips screw with the nut on it is the one you want. It is adjusted too far in and is putting enough pressure on the master cylinder plunger which is causing pressure to build in the brake line. If the rear is building pressure as well than there is something else going on there. I would begin with checking the tension on the rear brake link that attaches to the bottom of the brake pedal that puts pressure on the rear master cylinder plunger.

    This is the spot where the screw is on the brake side.

  9. freezbirid

    My husband's rear brakes has locked up about 3 times...

    Wow that dont sound good at all,but would think we would all have the same problem if it were the rubber hose getting hot,your the second one to have rear brake lock up whats going on here.Didnt your husband check it out to find the problem its a very basic system should of thought it would be easy to diagnose. Take Care John

  10. yhoower

    My husband's rear brakes has locked up about 3 times...

    I'm no expert on thermodynamics but I'm pretty sure that metal conduct heat better than rubber.

  11. 4mrAkankmpr

    I would suspect too little slack in the rear brake pedal linkage or else a warped disc. Then again, maybe your husband is resting his right foot on the brake pedal and 'preloading' the brake-its possible, he may not even realise he's doing it.(Just a thought).

  12. Frokkj

    Hi there. Thanks for the suggestions. His I could see, because he has a 2007 with 20,000 miles on it, mine is a 2009 with 4000 miles on it and neither of us had any issues at all until that last time the levers were messed with and the bushing put in to take up the wiggle room. I have a feeling their either contaminated the brake fluid or got air up in there and didn't bleed it out. I am not sure, but it really has made me lose faith in my bike for the moment, being new, you always feel you won't have any issues with it, at least for a while. So now until I know it has a clean bill of health, I won't be back on it any time soon. Brakes are surely not anything to mess with that is for sure.

    Thanks Frokkj

  13. JozhH

    Has anyone done anything to the rear brake system?

  14. ciwilkuj

    try another yamaha dealer to get a fresh set of eyes on the issue.

    even with 20k on the bike i still question the tech who bled and adjusted the brakes. this is too strange of an issue that happened to both bikes at relatively the same time. my money is on incorrect bleeding/adjustments.

    btw, since you overheated your brakes to the point of seizure, I'd have all the discs replaced and both of the brake calipers rebuilt to be on the safe side.

  15. dman

    What I can't believe is that the dealer addressed the issue and let you ride off on a bike that produced the symptoms on their test ride!

  16. divergil


    Make sure there is proper free play on the brake lever.
    During hot days, brake fluid will expand and cause locking up your brakes.


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