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XJ750 bleeding brakes!!

Discussion in 'XJ Technical Chat' started by Scottie1, Jan 18, 2018.

  1. Scottie1

    Scottie1 Active Member

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    Well after reading a few posts and seeing what a nightmare it is bleeding the Seca brakes I dove head in. Fitting new SS lines and used a mityvac thing on them. It took me 15 mins to do and low and behold they work. I was thinking it would be such a head ache to do but I guess I got lucky.
     
    Last edited: Jan 18, 2018
  2. cgutz

    cgutz Well-Known Member

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    I am not a mechanic, but with the help of these fine XJ'ers, I am amazed what I have been able to do.
     
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  3. Scottie1

    Scottie1 Active Member

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    They are some wonderful and extremely helpful people here. I belong to a Harley one to but they are not really helpful at all. Always being a bit rude when people ask questions.
     
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  4. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    Cool beans! Re-bleed them after 100 miles or so, just to make sure all of the air is out. Some of it likes to hide in the calipers somtimes.
     
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  5. Scottie1

    Scottie1 Active Member

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    Will do thank you
     
  6. Pizzaman

    Pizzaman New Member

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    I used the syringe method where you fill from the bleed valve. Worked great when I replaced my brake lines
     
  7. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    Well, you do have the least complex of the XJ brake systems. :)
    Single caliper, no anti-dive, easy-access master cylinder...
     
  8. cgutz

    cgutz Well-Known Member

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    I did the same thing, but found I should have "covered" the brake fluid reservoir. I ended up squirting brake fluid on the driveway and bike. Needless to say I washed the bike in a real hurry to save the paint.
     
  9. PJC750

    PJC750 Member

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    I have a Stuck slide pin on 1981 XJ750...There are 2 pins in each of the front calipers of this bike. Disassembly was going well until I got to the second. (By the way, use a small wood shim opposite of piston exit,(move fingers, cover with rag, bench vice is nice too)when you plug the bleeder to "air assist" the caliper piston out. Pin#1 that retains the Pads came out with a few taps on pin with allan key. Pin #2 (missing on diagrams), which holds the Slide is stuck. This pin has to come out to replace the 2 small grease boots. I removed the screw that holds the plastic cover...that was easy(clean the crud), hit the pin with PB blaster, took the tiny cotter pin out.The center part slides back and forth, but cannot rotate the pin to get it loose. After breaking an "ear" on a carb in a previous life, I now am "ear sensitive". This model Caliper has 2 big ears retaining the outer sides of pin. I made a brief attempt with a punch and small hammer, no luck. I also inserted small drill bit into the cotter pin hole, began rocking it to loosen...no luck yet. Any advice guys?
     
  10. chacal

    chacal Moderator Moderator Supporting Vendor Premium Member

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    Bigger hammer!

    Just kidding :)

    Use copious amounts of penetrating oil, and if necessary you may have to heat the caliper mounting plate (torch, etc.) and/or use freezing spray on the pin.
     
  11. LarryMc

    LarryMc Active Member Premium Member

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    To bleed the brakes to the next level, zip tie the brake lever down all the way and leave it sitting overnight. Its' amazing how much more brake action you get. This allows any residual trapped air to work its way out.
     
  12. PJC750

    PJC750 Member

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    Hi Pizzaman,
    I did reverse fill with syringe. Still no pressure at lever on My 1981 Xj750. May be MC not full?
     
  13. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

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    Did you rebuild the system?
    See my reply to your question here: #17
    Please start a thread for your bike, so we can help you better.
     
  14. PJC750

    PJC750 Member

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    Hi Guys,
    I just finished my front brake rebuild on 1981 XJ750. Thank you for the help XJ'ers for posting process, suggestions and solutions!
    Thanks to Chacal for your MC guidance, and hard to get parts. Regarding finding parts...there is a big "universe of original parts "floating around". Don't be afraid to try this method I learned. Call your local Yamaha dealer and ask him for your 20 year old part, of course he doesn't have "it". Kindly ask the parts person on the phone... " would you give a look on "Lightspeed", maybe a shop further away has it and I can call",There is a chance he will say..." Yes!", and after 10 seconds will add "Dirks Chopper store in Plattsburgh has one" Great may I have his number? Ask for the second vendor/number that he is staring at too. (It doesn't mean the other shop has the part...but this ancient parts system says he does) These parts are NOT on ebay or Amazon...they are sitting in a bin, dusty and forgotten! The only reason the dealer knows "he" has that part is because you called. He will be happy to sell it, Negotiate a fair price and you are a winner!....or a wiener as my wife from SA says : )
     
  15. PJC750

    PJC750 Member

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    Brake bleeding dry system for front brakes on a 1981 XJ750 Seca. I did total rebuild, added new Galfer line kit(4 lines, bolts and cr washers) new MC seals, and thorough cleaning. I used: One old glass pickle jar(get rid of label with goof off, so you can f-in see), keep the cap,punch hole in it with a punch(pencil size) for the rubber tubing(for when you kick it over(you will)). Place 2 inches of DOT 3 Brake fluid in the bottom and place one end of a 16" "soft" rubber clear line into the jar, below fluid level. The other end of the rubber line goes on the bleeder valve and fits tight! Nice! Now you can gleefully view the nasty air bubbles For refilling the reservoir, use a 100ml Syringe($4.00), attach another 8-10" of clear rubber hose (1/4"od) to syringe end and other will fit nicely into the 3/8"(hard to see) filler hole. If you own an 81, you get this. The rest of biking world, God Bless you... reservoir's on the handle bar! I did have to correct a leaky bleeder valve that was allowing air by the threads(re-seated and it was fine). I used standard bleed valves for the refill, you can add "speed bleeders" later, other people cover that process. I did a reverse bleed, using the syringe 3/4 full, starting with bleeder closest to the ground("AD" antidive bleeder). Remove the reservoir filler plastic screw cap(5 minutes), have them squeeze the brake lever, hold tight, begin pressing syringe plunger(10-20 ml worth)and have buddy watch and alert when filler is full of fluid. You will get fluid overflows...Old towels make great brake fluid rags, put em under/behind everything near an opening. With the reverse bleed, your only goal is to fill the system, don't worry about a mushy lever. Once you have reverse bled all 4, begin a standard bleed process, using the glass jar I noted. Bleed each valve,2 lowers first, then the 2 calipers. Repeat! I did this solo, so if you need to know, you will be doing 5 Steps: 1) pump brake lever(fully) 10x(build pressure) AND on last pump, hold lever against throttle(braking position) keep it there while 3) crack open the bleeder valve, watch end of the tube in the jar as bubbles exit(bubbles will slow to a stop), close off bleeder valve 4) NOW release the brake lever. 5) stand up, ck reservoir, top it off(Gotta love the rags!) Repeat this with the SAME valve (prob 4-5x) till bubbles stop. Now do the same with the other 3 valves. 5) Repeat the process with all 4 valves again. When you have completed the process a second time, the lever should be engaging the calipers to stop the front wheel. Check to see the system will hold pressure before filling, by connecting a hand pump to one of the bleeders(open). I did not have one of these, I simply checked banjo bolts, MC and reservoir were not leaking as I was filling the system....If everything is torqued correctly and bleeders are tight...you wont have air. Mushy lever still? Ck all of your fluid connections(leak??). Fun to know after all that work, the brakes are good!
     
    Last edited: Apr 17, 2018
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  16. LarryMc

    LarryMc Active Member Premium Member

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    Adding a bleeder banjo bolt immediately after the M/C is a huge plus. Bleeding the system became less of a pain by adding this $12.00 part. They come in single and double line configurations depending on your set up. I went with a stainless steel type fitting over the aluminum fittings after seeing an aluminum fitting shear off in a M/C.
    Its a real frustration avoider and an investment in keeping your sanity. Screenshot_2018-04-19-08-44-05.png
    This one is from Venhill....
     
  17. PJC750

    PJC750 Member

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    Where did you install....on one(or both) side(s) of the black block below the MC?
     
  18. LarryMc

    LarryMc Active Member Premium Member

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    2018-03-08 16.22.12.jpg
    It goes on the backside of the M/C. Bench bleed the master, install it, fill lines then bleed them, bleed the M/C at banjo fitting, then once more at each caliper. Done.
    Any residual air, and there will be some, can be expelled by securing the lever down with a zip tie and letting it sit overnight. It's amazing how much more action you get from the lever.
     
  19. LarryMc

    LarryMc Active Member Premium Member

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    I also have speed bleeder screws (check valves) on each caliper. I'm not completely sold on them doing what they claim they are supposed to do.
     
  20. PJC750

    PJC750 Member

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    Hi Larry, sorry mine is 1981, diff MC setup
     

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