No pressure in brake system

I have a kz400 1974. So I have changed my brake lines to Goodridge, also changed my master cylinder. I have been pumping and unscrewing the bleeding screw. I am trying to bleed my brakes. But there is no sign of pressure. When I fully unscrew the bleeding screw and pump the lever, the brake fluid sprays out. So the lines are working fine. What is wrong? Is there an air leak?

First thought: did you use 2 new copper washers for each banjo bolt? If not then you should get some. You may be able to pick them up at a local auto parts store. You'll need 10mm.

If the lever is losing pressure then brake fluid has to be leaving the system and air getting in to replace it. Air should not be able to get into the lines once you have the system completely bled unless brake fluid is coming out. Look for leaks. If you don't find any then try bleeding the lines again. Another way it might feel like it is losing pressure on the lever is if the lines are expanding but you have new brake hose so I would think that is not the issue.

I just installed a new master cylinder and a single brake line to my caliper for my 78 KZ400 this past weekend so everything is fresh in my brain. I removed the splitter with switch and went from 2 lines to a single one because my new MC has an integrated switch. But the process is the same in either case, just more connections to worry about.

Tighten up those banjo bolts, check the FSM for torque specs. Some people say you need to bench bleed the MC. I did not and did not have any trouble with it but YMMV. Yours seems to be pumping fine. For an initial bleed there are several options, some of them being installing quick bleed screws, using a vacuum bleeder or doing a gravity bleed. I did not buy quick bleed screws and I don't have a vacuum bleeder so I went old-school gravity bleed.

After adding some brake fluid to the MC reservoir and letting it sit for several minutes and seeing some air bubbles surface in the MC I then moved on to the next step. Squeeze the brake lever just a little bit and release it, you should notice some air bubbles surfacing again. Keep doing this until you see no more air bubbles. With a soft hammer or rubber mallet tap the end of the banjo bolt on the MC a couple of times and the end of the banjo bolt on the caliper a couple of times. If using a splitter do the same for it. Now go back to barely squeezing the brake lever again. Keep repeating the process until you see no more air bubbles.

At this point you will probably need to add some brake fluid again. After doing so place the lid of the MC back on. You'll be pulling the brake lever more in the next steps and you don't want brake fluid splashing onto your painted parts.

Feel around the bottom of each banjo bolt in the system to make sure there is no leaking brake fluid. If there is then tighten the banjo bolt a bit and wipe away the brake fluid. Be careful tightening them you don't want to strip the threads in the MC or caliper.

Next move on to manually bleeding the line and removing any additional air bubbles. If you have a vacuum bleeder then continue using that. Otherwise find a couple of feet of clear rubber hose that tightly fits over the bleed nipple. Drill a hole in the lid of a clear plastic bottle that the rubber hose will fit into. Put one end of the hose over the bleed nipple and the other into the bottle and set the bottle on the ground where you can see it and the hose. Ideally find a box end wrench that fits the bleed nipple. You don't need to turn it much to open it up, maybe somewhere between an 1/8 and 1/4 turn. Squeeze the brake lever and open up the bleeder until you start seeing brake fluid moving into the hose. Once it stops flowing then tighten up the bleeder and then release the brake lever. You don't want any air moving back into the caliper. Repeat this process until you see no more air bubbles in the brake fluid coming out of the bleeder and the brake lever has good pressure and is not spongy or does not fade (holds pressure for a few seconds but then fades and you can keep pulling the lever in). After every couple of times pull the lid off the MC and check the brake fluid, add more fluid as needed. You don't want to let it run low and introduce more air from the top end or you'll be doing the entire process over again.

Now go back and check each banjo bolt and connection again for any leaking fluid. If you find any then tighten the connection a little more, clean up the fluid, and continue bleeding to remove any air introduced from those leaks.

Once you have no more air in your line check that all bolts, screws and nuts have been tightened up (including the cap of your MC) and check the pressure of your brake lever again. Then roll the bike back and forth a bit and apply the brakes. Should be good to go.

Go back in several hours or a day or two to look for any leaks and to check the pressure on the lever again. Hope you don't see a puddle under the bike. Check all the connections again. If there are leaks then you may need to retighten and do some additional bleeding.

Hope that helps. Best of luck to you.

Is the brake bleeder at the caliper open to the atmosphere?

or do you have tubing connected & routed to an auxiliary brake fluid reservoir, such as a clean plastic bottle full of new clean fresh brake fluid. also, if you don't have a speed bleeder, that would be handy. you might be able to get one from the auto parts store.

I just did my brakes. A real pain.I was pumping for ages and getting nowhere.No idea why. In the end I attached a large syringe to the caliper and sucked the fluid through.Once that was done,I just bled the air out in the normal way.

If you can find someone who owns a tank type pressure bleeder you can make an adapter and use it. My wife bought me one (KD-2222) years ago for doing our cars, truck, and my bike. It makes the job very easy as it simply pushes fluid through the entire brake system non-stop until you shut off the valve. There's no lever pumping involved, you turn on the valve, open the bleeder at the caliper, and the tank does the rest. If you decide to do this let us know and I can give a tip or two on making the adapter. Ed

The master cylinder may be gummed up. Take the snap ring off, pull the plunger and clean with brake fluid. I did that with mine in 13 and it has been working since. I plan on a new kit for it but they are hard to find for this MC.
Steve

If you change the master cylinder and lines and try to pump fluid through, it will be near impossible as you found out. You need to get the fluid flowing to start bleeding. Probably the easiest way is a Mityvac or something to that effect that sucks the fluid in, then you can procede with bleeding. I've been down the road you are on and you can pump the brakes all day and try to get fluid flowing, but all you will get out of that is frustration.

What is the point of the splitter?

In some cases the splitter serves as a fitting so that a brake light switch can be attached. It also functions to transition the brake lines from the brake lever side of the bike to the caliper side. 2 short brake line hoses are probably less of a liability than one long hose that could flop around & get damaged.