Bleeding Brakes | Glass Jar Method

I've got a 1982 Yamaha Maxim XJ750J.

I bought it last year and got it running really well this spring.
The brakes have been real sluggish and m brake light finally came on.
I figured I needed to bleed the brakes and proceeded to do so.
I found out that the fluid inside was a nasty rust red-brown color so I
decided to flush it all (while still keeping some in the master
cylinder; and doing it all myself).
There was also tons of gunk in the master cylinder that I carefully dug
out with a flat-blade screwdriver.

The method I used was a glass canning jar with a hole drilled in the
top to insert a clear tube. I filled the jar with a few inches of
brake fluid and attached the other end to the caliper nipple. I bled
the brakes by opening the nipple, squeezing gently on the brakes, and
then holding the brake in while closing the nipple. I did the process
successfully for a while, getting out all the old fluid.

My problem now is that I cannot seem to get the new fluid to go down to
the calipers. I filled the master cylinder up and pumped numerous
times but I get no pressure. I tried to open the nipple with my
contraption attached and brake fluid/air mixture comes out...

the problem is that when I close the nipple with the brakes depressed,
then release the brakes, then open the nipple again... it sucks the
mixture right back in. It didn't do this when I originally bled the
brakes. I'm guessing it has to do with a pressure difference. Any
ideas on how get the fluid to feed down the piston in the master
cylinder and into my lines. Any idea about the mixture being sucked
back up by the caliper?

Does anyone recommend pumping some brake fluid up the caliper into the
master cylinder? How would I go about this without introducing air
into the line? Do I need to worry about air in the line since I am
forcing the air up and out of the master cylinder? Thanks!

 

Forget the bottle system, or the submerged aquarium air line bit, air
just leaks around the bleeder screws.

I wonder what it is with motorcycle engineers, that they don't install
a banjo bleeder right up at the master cylinder outlet where you need
it. Instead, they put the bleeder screws down at the calipers, which is
stupid in my opinion.

You can crack the banjo bolt loose and pump the air out of the high
point of the system, but put a rag undeneath the banjo because brake
fluid eats up paint.

When it comes right down to the nitty gritty, you do not need those
caliper bleeder screws anyway, after you get the caliper full of brake
fluid.

If you unbolt the calipers and let them hang straight down, you can put

a piece of 1/4 inch steel plate between the pads to keep them from
blowing out as you pump the lever, all the air bubbles will rise up the

hoses to the master cylinder reservoir.

That's how I bleed brakes.

Google for "bleeder banjo"...

I think Galfer or some manufacturer of steel braided aftermarket brake
hoses makes banjo bleeders for about $15 USD.

The main idea for the banjo bleeder is to install it up at the master
cylinder so you can bleed out the air bubble that accumulate in that
critical area.

Air bubbles right there cause the front brake lever to feel spongy and
riders keep trying to bleed the air out down at the caliper and have no

success getting the air out.

For some reason, riders (and engineers) don't seem to understand that
air bubbles rise
and brake fluid goes to the lowest point in the system.

If you find metric banjo bleeders, they will probably come in 10 and 12

millimeter diameters with two or three different thread pitches. You
must get the correct thread pitch or you'll just cross thread the
damned things. Thread pitches are typically
0.75 mm, 1.0mm, 1.25mm and 1.5mm, with the most common used being 1.0mm

between threads.

 

The glass jar method makes it so you don't have to keep opening and
closing the bleeder. (Hence the moniker 'one man bleeder') With the tube
submerged in the old fluid, air doesn't get back in when you let go of
the lever. (Except, if you leak around the hose to bleeder screw. I
throw a wrap of wire around it to help reduce incursion. Also, just
crack the bleeder screw so you don't get leakage at the threads.)
You state the master was full of gunk. It is VERY easy for the fluid
return port to get clogged. If it does, you might experience what you
are describing. You will most assuredly experience brake drag.

I really recommend vacuum bleeding from the bottom up. Beyond the means
of most home wrenches, however. I've very successfully bled with the
bottle for years.

--
Gopher Greg
'77 CB750K Stock '78 CB750K AHRMA
'00 ZG1000 Stock '96 Ducati 900SS Former track bike
'01 GSXR750 Current race bike
**********pull 'mychain' to reply***********
("I've abandoned the idea of trying to appear a normal, pleasant person.
I had to accept myself as I was, even if no one else could accept me.
For the rest of my life I would continue to say precisely the wrong
thing, touch people in the raw and be generally unpopular. I had a
natural gift for it" W. F. Temple)

 

nomorespameventhoughthejapanesespamgivesmeachuckle

<snip>

The way I've done it for decades is to use a single pipe. Place pipe on
nipple, pump lever half a dozen times, open nipple while holding lever
in, close nipple, release lever.

Repeat.

It works.

If at any time you release the lever while the nipple is open, you will
suck in air.

 

My problem now is that I cannot seem to get the new fluid to go down to

First a caveat - I have only dealt with (what are now) old
cars not bike brakes. Same stuff tho'?

"then open the nipple again... it sucks the mixture right back in"
This could occur if the passage for fluid out of the resevoir
into the master cylinder was blocked. In the case of bikes the
resevoir and Master cyl are often combined into one package
but the seperate functions are still there.

- Press lever - fluid comes out of bottom
- Close bleed valve
- Release lever
- The piston in the Master Cyl /should/ now return
and fluid should flow to the front side of the piston
via valves in the piston s it returns.

It appears as if this last step is not happening.

Brake bleeding is usually simple when everything is
working OK.

In my experience the most common cause of an inability
to get brakes to bleed is a faulty master cylinder which is
allowing air past the lever end seal.

When the lever is released the front (pressure) side of the
Master cyl is connected to the resevoir so the system is
open to the atmosphere. (Ah! Maybe there is a difference
betwen bikes and cars here since the bike resevoirs
seem in some cases to be completely sealed?)

 

"nomorespameventhoughthejapanesespamgivesmeachuckle"

The way I read your description, you are opening the bleeder screw before
you put pressure on the brakes. This is where your problem lies. Never
open the bleeder screw until you have pumped up and are holding pressure on
the brake lever.

Pump up brakes and hold pressure on lever
Open bleeder screw slightly (just enough for the fluid to come out)
When lever bottoms out, close bleeder screw.

Repeat over and over.





It didn't do this when I originally bled the

 

The problem was as Just Some Guy stated. I wasn't compressing the
brake lever before I opened up the bleeder screw. I ended up bringing
my neighbor over last night to help and he knew a bit more than me
since he has done this on cars. We got a nice tight lever (great
pressure); unfortunately I woke up this morning to find spongy brakes
(almost no brakes) - there was still air in the lines.

I had my bike in the shop last week to mount and balance a new front
tire and they had mentioned that my calipers were sticky. I didn't
have them work on it right then because I really wanted to ride that
night and they said it wasn't critical to fix them then.

After flushing the breaks the motorcycle started to act real bad under
20mph: constant pushing and pulling and needed to rev to 2500rpm just
to go from standstill. My guess is that one of the calipers was
sticking and found out that the left one was because the disc was HOT
to the touch after just a few minutes of riding. Sooooo, I took the
bike into the shop again to have them look at the calipers and
clean/rebuild them... and then they'll bleed the brakes for me too =).

For interest, how hard would someone say it is to clean/rebuild the
calipers myself? I will do most things on a bike but messing with the
calipers/pads is something I don't want to mess with myself (unless
someone experienced is showing me what to do). I know it's a relative
question, so please answer it relevant to working on other aspects of
the bike and not ones personal experience; a.k.a if you've been working
on bikes for 20 years don't just say it's easy =).

 

I would say that disassembling and cleaning a brake caliper is
extremely challenging to most riders.

We are talking about messing about with the brakes, and improperly
repaired brakes could cause a bad accident

Motorcycle mechanical assemblies are not very intuitive, and an amateur
mechanic often needs to be
creative about making home made tools to avoid having to buy expensive
special Yamaha tools that
he might just use once and never need again.

You might be better off just removing the calipers and take them to the
shop and let an experienced mechanic rebuild them.

A real klutz could still get himself into serious problems by cross
threading banjo bolts and
attachment bolts, and the latter are supposed to be installed with a
torque wrench, unless you have a
"calibrated wrist" like many old timers have.

I looked at the front brake caliper diagram on www.partsfish.com. You
can register and look at diagrams for free there, or you can go to
www.bikebandit.com.

I can see that the calipers are single sided, each caliper only has one
piston, one o-ring and one dust seal (# 7, caliper seal set).

I can see that the caliper bracket is held to the fork legs by four #
19 bolts. And the half of the caliper slides sideways on the # 11 and #
18 pins. Those pins are supposed to be greased with a high temperature
grease.

I cannot tell from looking at the drawing if there are bolts that hold
two halves of the caliper together, or if you can just remove the brake
pads, remove ONE brake caliper from its fork leg, and just pump the
piston out of the caliper by working the brake lever.

There is nothing in the pressurized half of the caliper except the
tightly fitting piston, a dust seal, and a square o-ring.

You could use some fine emery cloth to clean rust off the piston and
out of the piston bore, then lubricate the piston and o-ring with clean
brake fluid and reinsert it into the bore.

The fit on the piston is very close, it won't go back into the bore
unless it is perfectly straight. It won't go in if it's even slightly
cocked.

After you finish reassembling and reinstalling one caliper, you can
bleed the air out of the system and then fix the other side, again
using the brake master cylinder to pump the other piston out of its
bore.

Sometimes brake caliper pistons are reluctant to go back into the bore,
and you can sometimes use a small c-clamp to push them back in. Use a
thin piece of wood on the aluminum caliper body to avoid
scratching it with the clamp. A mechanic in a shop might use an arbor
press to push the piston back into its bore.

 

nomorespameventhoughthejapanesespamgivesmeachuckle

It's simple but if you can't bleed brakes properly, I'd suggest leaving
it to someone who knows.

The simplest task is to remove the slider pins that the horrible old
Yamaha single-piston calipers ride on, clean them, apply copper grease,
and then reassemble.

Also - remove caliper, pump brake lever a few times to force out the
piston a bit, clean round piston with toothbrush, push back piston,
repeat a few times until all the crap has gone. Makes a big difference.

 

On a Maxim brakes it's very, very simple. One piston per caliper (knew
that without having to look it up, having owned several Yamahas of that
era - they all used the same basic caliper).

Oh yes. If you don't know, don't do it.

You don't need any special tools for a Yamaha Maxim caliper strip.

Probably.

 

"nomorespameventhoughthejapanesespamgivesmeachuckle"

It is pretty easy, but there are some tricks to it and it is messy, and
brake fluid eats paint. I
just did this recently as a matter of fact with my CB750 when I
first bought it. I gambled though, because I did not buy the
rebuild kit or replace any of the seals or anything. I just took
everything apart, all seals apart, and cleaned it with brake fluid
and scrubbing at it with a cloth. It takes a long time that way, but
if you can get it clean that way then you can sometimes get lucky and
reuse the seals. I got lucky.

Ted