Front brake won't brake

[Bo]

Hi,
I'm back on the forum to ask my questions...
I rode the bike a little bit, but I was braking only on the rear brake as the front one won't do anything (or so little).
I took my Haynes, and saw I should bleed it. What was coming out was so dirty that I did it until neither bubbles nor dust came out. I proudly tighten everything (I had some difficulties to find such a tiny wrench), started the bike, and it doesn't work better.
So I'm asking for help, what should I do? When bleeding, I saw that some liquid is coming back to the reservoir when I brake (the level slightly increases). Is that normal?
Thank you!
Bo

[ArrrGeee]

ok, I'll give you?some ideas and some suggestions.
First off, do not, I repeat, do not ride the bike without
front brakes, you will die. the front brakes are 80 to 90
percent of your stopping power, without them you're dead.

ok, now that I've said that, it sounds like your hydraulics are shot. ?there are many posts here on the board about bleeding brakes that probably describe the process better than I can but if you cannot get a solid feel to the brakes, assuming you got all the air out, you've got to overhaul them. that means completely disassembling the master cylinder and caliper(s).
cleaning them out, checking the bores for scratches and pitting and replacing all the rubber parts if they are not in good shape and\or the complete units.

it's my opinion that if you are not comfortable doing a project like this that you should get some help doing it or have a shop do it for you. the kits for cailpers are around 55 bucks from yamaha and include new pistons. I haven't priced out a master cylinder kit lately so I don't know what they go for. ?I'm quite serious about this, the only thing between you and major disaster is your front brakes, do them properly or have them done by someone who knows how.

if you understand all of that, ?check the links page, you can probably save a couple bucks by buying online or checking out ebay for what you need.

now to answer your question, the reservoir should be full.
you can see some fluid movement when you squeeze and when you let go. that is normal. sometimes it helps to bleed the master out first before going down to the calipers.
squeeze the lever 3 times, hold it down, crack the fitting for a second, then tighten it up. watch for bubbles. do that 3 or 4 times then move down to the caliper(s) do each one the same way. when you crack the fitting to let the fluid out, try not to let the handle bottom out.  there are other ways to do it with a bottle and some rubber hose is the way I like to do it because it is neater with less chance of spilling fluid on your paint job. brake fluid eats paint.

-Ron

[JaBey]

deja vu!!!

http://www.ghetti.net/cgi-bin/ROVBB/YaBB.pl?board=general;action=display;num=1078703618

 ???

[Bo]

Yes, sorry, it's quite the same problem, except that I bleed the brakes since these posts, and it doesn't turn to be better.
I guess I should have continued the former topic about it.
The wether is quite bad this week, but it only means that I can't work on the bike (I don't have a parking place, and my roomates won't let me work on part of the bike inside)...
To do this project, I would effectively feel more comfortable with a "clean" place to do that, but as I already did this kind of work on my car, my main problem is that I don't know where the valves are located on the bike, and that I have to find the right translation of the name of the part before I get the information from my Haynes.
That why I'm so happy to find guys like you, who explain to me so clearly what I should do!
So thanks a lot for all this help!
Bo

[Bo]

Hi,
I opened the master cylinder.
the "rubber dust boot" seems bad, bud nothing leaks.
But the piston looks weird!
http://www.ifrance.com/boandmotorcycle/
What afraids me is the "broken" part next to the cup seal on the spring side.
Can I still use it, is it worth going to the Yamaha shop to buy some parts?
Please help!
Thank you
Bo

[RobTx]

Definitely need a new piston and seals.  Dennis Kirk sells a rebuild kit for the Vision master cylinder for $26.99.
http://www.denniskirk.com/jsp/product_catalog/Product.jsp?skuId=191750&store=Main&productId=p191750&catId=4&leafCatId=41007
Rob

[JaBey]

I concur with Captain Rob:-) By the look of that piston, I wouldn't put new parts in that cylinder without seeing about having it honed. The corrosion will only rip your new boots.

[Rick G]

I have master cylinders , that I have serviced and will guarentee, for a reasonable price. Email me if you want one.  

[ArrrGeee]

nice find Rob.
it looks like it fits only 82.
I can't seem to find an 83 kit on their site tho'
anyone know where I can find one of these? besides the dealer that is....

-Ron

[Bo]

Ok,
I rebuild the master cylinder (with a kit sold by a salvage shop, that also have new parts). I checked, the piston are exactly the same (I read the post before and was afraid it would be the 83's one).
I went to bleed it, but nothing's coming out. I disconnected the tube from the master cylinder, I can see the spring moving with the lever, but nothing's coming out. Some bubbles are coming from time to time through the hole at the bottom of the reservoir. I tried half ann hour long to "pump" by holding/releasing the lever, but still nothing. Is there anything you guess I did wrong? Is there a way to start bleeding? I could find that neither in my Haynes, nor in the previous post about bleeding (the procedure worked well before I rebuild the master cylinder).
Thanks
Bo

[Walt_M.]

Did you check the bore in the master cylinder before you put the rebuilt piston in? Your old one looked pretty bad in the photo and the bore could be bad. Also, was the rebuilt piston assembled properly? It should look like the photo, without the damage to the outboard side

[Bo]

I check the bore, that look nice. The new piston looks exactly like the old one (or the picture in the Haynes, it's the same). All the parts fit exactly, the seals were quite difficult to put into the right place, but it's done. Nothing's leaking, put nothing's getting out too. I tried to put back the old one, as I use to be able to bleed with it, but it doesn't work too. Th only thing I can see are some bubble when I start to try
I have two hypothesis:
I either I need to have fluid in the system before I put everything together (I don't know... pressure difference coming from the fluid sucking...). I'm quite sure I don't have fluid neither in the caliper nor in the line anymore.

II or I did something wrong, but I can't figure out what.
What I did:
I cleaned the master cylinder with brake cleaning fluid, then with some clean brake fluid. I let the new piston 10 min in the clean brake fluid.
Empty all these fluids, put the piston into the master cylinder, push it all the way long, then put the snap ring as far as I could. Put the dust boot, put back the handle, put the master cylinder on the bike, plug the switch for the brake light, and the line going to the brakes. As the level in the reservoir didn't change when trying to bleed, and the lever was always loose, I removed the line, and nothing was going out from the master cylinder.
Then I took back the master cylinder, tried to remove and put again the parts, then tried with the old one....

Thanks for helping!
Bo

[Walt_M.]

Did you put the spring back in before the piston?

[Bo]

Excuse me
Yes I did, but forgot to type it!  ;D
Bo

[rick_nowak]

sounds like the mc is not self priming.  what you can try is pumping fluid in from the bleed screw on the caliper.  use a new pump oil can and a length of suitable hose.  put fresh brake fluid in the can, push the hose over the bleed fitting and crack the fitting.  pump the oil can.  it will be really hard but you should be able to get fresh fluid everywhere.  if that is too hard to do, then crack the line at the junction bolted to the fork.  bleed that out.  then tighten and crack the line at the mc.   bleed that.  tighten that up and then push the fluid into the mc.  have the lid off the mc while doing this.  the vent is really small
while you are doing all this remember that brake fluid is corrosive to paint and do whatever you need to keep the fluid off paint.
motorcycle brakes are notoriously difficult to bleed compared to cars.  most shops have some sort of pressure bleed system that they use.  the pump oil can is just a variation of that.

[GarysVision]

hello
well let me start out by saying trying to do your on brakes is not a good idea if you are not very sure of what you are doing.
what i have did is ( not worrying about the money) when it comes to your brakes you cant skimp but i just orderd a brake line kit i have converted my 82 brakes to 83 so i have 2 rotors up front now with steal lines you can get pretty cheep and build them your self and for the master cylender i took one off a wrecked honda CBR600F2 and they work great just about put me over the handle bars. the whole thing cost about $150.00 doing it my self and my brakes work better then they ever have. but the main thing is never rush it just take your time you can not rush it.

[Paul_Jungnitsch]

From what I remember the feed hole in the bottom of the reservoir that goes into the master cylinder is very small. You may want to check it didn't get plugged with swarf when you cleaned the reservoir out.

Once things are working make sure the cover is on before bleeding, or the fluid goes straight up and gets everywhere!

[Rick G]

I tape  a trash bag on to the gas tank , anytime I  add or check fluid. an old towel keeps any splash from running down.

[Bo]

Hi guys
Thanks, it's finally working! I spilled some brake fluid on my tank, but I already had to repaint it, and I saw that one of you get a website on that.
I still have a question: testing the electric components on the bike, one of -I think- coils, reads infinite resistivity when I test it the way described in my Haynes manual (the component is the one of the picture 22.4 page 149). Can I ride my bike to the shop to buy one - at least 30 miles, I'm in Oklahoma  :(
Thanks again!