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Squishy Brakes

Discussion in 'The Garage' started by Solomoriah, Aug 19, 2018.

  1. Solomoriah

    Solomoriah XS650 Addict

    Okay, so I mentioned in my build thread (and elsewhere) that my XS650 arrived with a nasty, leaky, ugly master cylinder. I decided to do what I did with my Honda CB650, namely put on an aftermarket unit from a vendor I trust. When I posted my intentions on this forum, I received numerous suggestions to use a master cylinder with a smaller piston (14mm being stock, as I understand it). So I did.

    To be clear, the front brake basically didn't work when I got the bike. Putting on the aftermarket unit and bleeding the system resulted in me being able to lock up the front brake while rolling the bike around manually, but the brake doesn't have the positive, solid feel that I got from the replacement I put on the Honda. The lever does not come back to the grip, and I see no fluid leaking out anywhere (nor does the level seem to be going down in the reservoir).

    I bled the brakes a second time and got a few very tiny bubbles, but this made no change in the behavior of the brake; if I didn't have a really solid rear brake, I wouldn't dare ride the bike at all. It feels kind of squishy, honestly.

    There are several possibilities, of course. The replacement unit, a different model than I got for the Honda, might not be as good, or it might be defective. I don't see any sign of the latter, though; the only defect I can imagine in it would be if the piston leaked fluid back into the reservoir, but if it did that the lever would eventually touch the grip as it lost pressure. Secondly, the caliper could be bad somehow, though I don't know how; third, one or both of the original brake lines could be bad. I'm leaning that way, honestly, but I'd like some extra opinions before I buy any more parts.
    gggGary likes this.
  2. 5twins

    5twins XS650 Guru Top Contributor

    Yes, you need to replace the brake lines, they're 30+ years old. That will probably fix the issue. Many of us switch from the original 2 line config to one long single line.
    grizld1 and gggGary like this.
  3. grizld1

    grizld1 Grumpy old man Top Contributor

    You must use braided stainless lines with the smaller mc if you want decent feel. Ever look at a factory service manual for any Japanese motorcycle, from the first disc brake offerings to the present day? Every one I've seen specifies 4 years as the service life of rubber brake lines, and most guys, including guys who ought to know better, ignore it. There is no max service life for braided stainless lines.
  4. Solomoriah

    Solomoriah XS650 Addict

    Well alrighty then! This jives with my impression, actually.

    As I understand it, the non-Special US XS650's use a pair of 20" long brake lines; can I assume that my Special, equipped with lower CB750-style bars, would be good with a single 40" line?
  5. Solomoriah

    Solomoriah XS650 Addict

    ... so I've been doing some looking, and noticed that Dennis Kirk has this:


    It's on closeout for a decent price, and has the fittings already fitted (and includes all hardware, apparently). This is a pretty darn good deal, but it's only 37" long.


    Now I get to go home and try to figure out if that will reach or not... because if it will, I'm buying it. I see no reason the 35 degree bends at each end will be anything but fine, IF the hose reaches.
  6. Solomoriah

    Solomoriah XS650 Addict

    Well, I'm just going to keep replying to myself here.

    I took a length of clear utility hose I had lying around, measured it, and wrapped tape around the 37" mark. I twist-tied that point to the brake line at the master cylinder, then ran the hose down to the caliper. It's a couple of inches longer than strictly necessary... so the discount Goodridge brake line I linked above should work fine.

    At least, that's how it looked. But the description for the part matches the photo, namely, it's a 4" long piece of brake line. WTF? The detailed description says it's 37" overall length. One or the other piece of information is wrong... gah.
  7. Solomoriah

    Solomoriah XS650 Addict

    ... and now, I've found an alternative. Here's hoping it is, in fact, those crufty old hoses. I ordered a 1000mm braided steel brake line, fittings included. Thanks for the advice, guys!
  8. delagem

    delagem XS650 Addict

    Always worthwhile to change the hoses.

    However, every time I've had squishy brake lines like you describe, it's always been an air bubble trapped at the upper banjo bolt, where the hose joins the master cylinder; it's very difficult to get an air bubble trapped there out.

    You could buy a banjo bolt with a bleed nipple. I run them on some of my bikes. But I've also had very good luck with, as a last step in bleeding the brakes, to just barely crack that banjo bolt, while gently squeezing the brake lever. Put rags, paper towels, a trash bag, or something under it, to protect the paint.

    As you loosen the bolt, you'll hear the snapping sound of air bubbles spitting out, then it'll just ooze brake fluid. Tighten it back up before you stop squeezing the lever. Done.

    Good luck!


  9. Solomoriah

    Solomoriah XS650 Addict

    Thanks, delagem! I'll keep that in mind as I install the replacement hose. One way or the other, I'll have this working right eventually.
  10. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

  11. Solomoriah

    Solomoriah XS650 Addict

    650Skull, thanks, I think that's actually what I just ordered, but from a reseller who will give me free shipping. $14.00... I can live with that.

    ... just ordered one of those bolts with a bleeder. Again, thanks, delagem!
  12. ThatXS650Guy

    ThatXS650Guy More Sparky than Speed Racer XS650.com Supporter Top Contributor

    North GA
    It's important to make sure the fittings are correctly oriented. I ordered one of those cheap Banggood lines and the fittings were off 180 degrees. I like the hoses Mike's XS sells because you can order what ever end you need and they will swivel to wherever you need them to be.
  13. Solomoriah

    Solomoriah XS650 Addict

    Well, I can only hope at this point. But I can return the part, and even if I don't it was pretty reasonable.

    A single brake line makes way more sense than using two segments and having that fitting in the middle. I mean, I know why it's there (to handle dual discs where installed) but for me, there's no point to doing it that way. Costs more money, and has more things I have to futz with.
  14. 5twins

    5twins XS650 Guru Top Contributor

    The best orientation for the fittings on your line will depend on where it connects on the MC. The lines Skull linked to have the fittings in the same plane. That type works best on a MC that mounts the line on it's front side. The stock MC that mounts the line on the end works best if the fittings are offset 90° to one another. Banggood used to sell a line like that but I don't see it listed anymore, only the ones without offset ends. I got one of those Banggood offset lines about a year ago and just installed it recently on a stock MC (end mount). It fit and works well .....



    I have lower than stock Euro bars installed and use the 90 cm (about 35.4") line length.

    This is a front line mount MC I installed on my other 650 last year. I'm using one of the lines Skull linked to above with no offset on the ends. Again, Euro bars, 90 cm line length, it fits and works well .....



    On either set-up, a plain straight fitting with no angle bend works fine at the MC but you do want a small angle in the caliper fitting to better clear the bleed nipple .....

    grizld1 likes this.
  15. Solomoriah

    Solomoriah XS650 Addict

    The line I ordered has a small bend at each end; until I try it, I really don't know how it's going to fit. As I say, cheap enough that I can try something else.

    Incidentally, it looks like you're running the same master cylinder I have. I think my bars are wider than yours though; hopefully the extra length (I got the 100 cm brake line instead of 90) won't be an issue.
  16. 5twins

    5twins XS650 Guru Top Contributor

    Mine's a used eBay find, an 11mm bore off the Yamaha XT/TT225. It might come on the TW200 as well. Honestly, I think it's a bit too small, you have to pull the lever about half way in before anything happens. It does give better modulation and "feel" than the stock 14mm bore but all that wasted lever travel bothers me. I do a lot of 2 finger braking, mostly for scrubbing off some speed when going fast. It's difficult to do now with this MC because the lever comes in so far, it tends to hit my other 2 fingers still wrapped around the grip. Everybody raves about the 11mm size being the hot set-up. Frankly, I'm not that impressed, lol. I may try a 1/2" (12.7mm) bore one next. That might be the perfect compromise, slightly smaller than the stock 14 but not too small. A bit better "feel" but hopefully without all the extra lever travel.
  17. Solomoriah

    Solomoriah XS650 Addict

    Okay, so you don't have the one I have... although I do have a TW200, so I might have one there. I have a 12.7mm unit meant as a replacement for smaller Honda bikes, apparently; it's the same very basic Chinese castings as many eBay replacements, but the parts are assembled and tested in the US. At least, that's what they say, but I've had excellent results with the 14mm unit I put on my CB650, which is why I bought another from the same guys.
  18. aldo5468

    aldo5468 Redleg XS650.com Supporter XS650.com Supporter

    TV antenna cable also works well to determine what length of brake line you need - it will hold curves as you route it between the m/c and brake caliper, just need to allow enough slack when forks are extended fully.
  19. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Just to add to this thread.
    Did several "apehanger" kits back in the day. Longer cables, wire extensions, longer brake hoses. Would occasionally get the "squishy brake". All those kits used rubber hydraulic lines, some of questionable quality.

    The test was to grip the brake line, like holding onto a rope, and manipulate the brake.

    If you could feel the brake line swelling within your grip, get rid of it.

    Same with any stock or aftermarket hoses...
    robinc likes this.

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