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**randy** · 07-22-2004, 12:44 PM

Before you get out the BFH, you may have been sucking air INTO the bleeder from the loosened threads. When I bleed with vacuum, I pack grease outside the base of the bleeder where the threads enter the caliper. That prevents air from coming in.

Next, when you bleed, do the bottom hose first. Let me clarify. The union omn the lower triple tree has one hose at the bottom. Do that one first. Then do the other caliper.

HTH

randy

**beechfront** · 07-22-2004, 01:57 PM

hey randy.

good advice on the grease. i now do not see any air coming through. did around 5 reservoirs full for each caliper. then went through and bled the old fashioned way for 3 or 4 reservoirs.

still no brakes.

toward the end i could hear some noise coming from one of the calipers but i could not tell which one. could there be a problem there? could it be something with the new master cylinder i got that is causing me problems?

i have been fighting this for about 6 hours solid. not counting last night. i have done a lot of work on this bike but this is the most frustrating so far.

**randy** · 07-22-2004, 02:26 PM

I hate to be the bearer of ****ty news, but I would pull the piston from the Master to be sure the cup(s) haven't been disologed from their proper places. Sometimes vigorous pumping and fully bottoming out the piston can dislodge them.

Other than the things you've already done, that is the only reason I can think of that you don't have brakes.

HTH

randy

**beechfront** · 07-22-2004, 04:58 PM

i am using a brand new master cylinder though.....

looking inside the new one where the line connects it is different. on the original it was completely open. on this new one it tapers down.

i have no idea what to try now.

i'm a pretty calm person but i cannot work on this thing anymore or i am going to lose my temper.

**beechfront** · 07-22-2004, 05:48 PM

is the "cups being dislodged from the piston" syndrome unique to the XS master cylinder?

I even forced brake fluid up from the bottom - filling then emptying, filling then emptying the reservoir. after that I would bleed the old fashioned way repeatedly. and nothing.

i am thinking the cups on this new unit are dislodged, as you said - or it is not compatible for some reason. brakes are a whole new world for me. am not enjoying it so far.

this was the last thing I was going to work on before my big trip next week. i don't want this to keep me from going.

**ratbyk** · 07-22-2004, 06:01 PM

Master Cylinder Problems

Beechfront, put your old master back on and try it. If it builds pressure you know the new one is defective.
Have you tried a trick that I suggested previously of removing the master from the handle bars. Leave everything hooked up. Tilt the master to a more vertical position and then try bleeding. Air trapped in the bore of the master that is causing your problems will move to a new position and you will be able to expel it.
You could also remove the new master and bench bleed it. Take the removed master. Clamp it in a vice. (Gently even if you are mad at it.) Now bleed it by using hand pressure on a Philip's screw driver to force the piston in. As it bottoms on its stroke put your finger tightly over the line hole and let the piston return to its rest position. 3 or 4 strokes is all it usually takes to start creating pressure. If you cannot create pressure on the bench you are not going to on the bike either.
Also, don't pump like crazy. Just smooth steady strokes. Pause at the end of each stroke momentarily to allow new fluid from the reservoir to enter the cylinder bore. Pumping away madly will only aerate the fluid and you will never create good pressure.
Ken/Sooke

**beechfront** · 07-22-2004, 06:20 PM

yeah i tried your suggestion. had it filled completely full, tried many different positions. i did get quite a few small bubbles out through the reservoir by doing this and lightly squeezing the handle.

guy at the local shop said to hang it, handle pointing up for a couple hours. also showed me a trick to force fluid up through the lines from the bottom.

i don't have a vice so can't bench test. i am 95% sure that i have gotten all the air out of the line.

the old one was not as bad as this one. i could at least pump it 2 or 3 times to get good stopping pressure.

**gaffer77** · 07-22-2004, 06:28 PM

hi there i hope im not being a nob here ive read my books ,if you pull lever to far you have to reset the plunger in the master cylinder also pull lever slowly ,once you have got pressure i pull with a cable tie and leave it over night this forces air to the top i had grief like you got on a mates kwaka and i know wat u r gooing through i havnt read evthing youve written just wanted to tell you this incase you didnt know

**beechfront** · 07-22-2004, 07:19 PM

alright - if the plunger is out of place will i get any pressure at all?

how difficult is this to get apart to check? i cannot see how to get to any of the innards.

i took it for a short ride around the block. i will give me very very little pressure first pull. 2nd, 3rd, & 4th just a little bit more but still pretty worthless. it will hold the pressure though if i keep holding the brake down.

**ratbyk** · 07-22-2004, 07:43 PM

Weak Brake

From your last description there is still air in the system. Keep chasing it.
Another trick I have used with good results is to take a short piece of vacuum line or similar. One that fits tightly over the bleeder screw. Fit this onto a loosened bleeder screw. Loop it back down into a small jar with some brake fluid in the bottom. Now slowly pump the brake lever, again pausing at the end of each stroke. As you apply pressure, fluid and air should be expelled. On the return stroke only fluid can be drawn back in. You should see a stream of bubbles on each stroke gradually diminishing as more strokes are completed. When no more bubbles appear go three or for more strokes and then switch over to the other caliper.
Do the left front first (farthest fro master) then do the right one.
Put a block of wood or something under the jar to raise it up near the caliper to keep your hose length as short as possible.
Ken?Sooke

**TopCatGr58** · 07-22-2004, 08:06 PM

Hey there Beech,

Stupid question, you say it's a new MC, where and what type is it? What was the piston diameter? Our old OEM's IIRC were rated something like 16mm. I just checked DK's, their's is only 13mm, which means it would pump less volume per stroke!! The one on Partsnmore is rated at 16mm for dual disc front brake systems, designed to pump more volume.

You could try pulling one caliper off and connecting it directly to the MC with just a single hose, then bleed and then see how much pressure you can develope with just one caliper to feed fluid to!? If you then get pressure and a firm handle, then you know the MC can develope pressure. Then reattach it to the dual lines and both calipers, bleed and see how it does. If it still take several pumps but will eventually get pressure, then it may be that your MC isn't big enough to pump enough volume of fluid into both caliper assemblies to adequately create the pressure and firmness in the brake lever!?!?

I bought a MC from a salvage yard, was for a Yamaha, but not XS, and I think it was for a single caliper system, I, too, have bled it thoroughly, and mine takes a few pumps to get it to be moderately firm, but I can still almost touch the end of the brake lever to the handlebar, the front wheels WILL LOCK, but the lever doesn't feel as firm as the OEM unit used to. I'm thinking of replacing it with the Partsnmore unit, but I was just wanting to get mine on the road 3 years ago, so I settled for the smaller one!
HTH? T.C.

**2fast** · 07-22-2004, 09:00 PM

I agree with gaffers comments. I had this exact problem when I did my brakes and rebuilt the master cyl. If you over stroke the master prior to getting pressure the cups can get dislodged and stuck in the stroked position. Take it apart and reassemble it, and start over using very short strokes. All you need for taking it apart in the way of special tools is a circlip pliers (cheap).

**beechfront** · 07-22-2004, 09:28 PM

thanks everyone for all the input.

went to take it apart - tried to pull out the cylinder and it's not going to move easily. could not see a clip or anything holding it in. didn't want to force anything at this point.

did do some more bleeding / different angles. even took the calipers off and held them at various angles to bleed. i am still not getting one bit of air out of the lines. (ratbyk - thanks for the advice - but that was the first thing i tried at 10:00 this morning

)

i looked and it has a 13 stamped right on it. it also seems really cheaply built in my opinion (if a mc can be cheaply built). if that is the problem perhaps it is even a bit weaker (cheaper) then your 13mm yamaha mc topcat? for now i am going to assume this is the problem and go back to local shop and tell me he sold me the wrong thing. i figure i am going to want a 16 mm regardless. hopefully he can take it back. if i order the one from partsnmore tomorrow, should be here by wed or thurs at latest. hate this last minute stuff.

i'm not ruling out the plungers being dislodged - but if there is a chance i can take it back and get a larger MC i would rather do that instead of taking this thing apart and risk screwing it up. probably have better luck bleeding with a larger MC anyway.

**gaffer77** · 07-23-2004, 03:41 AM

i read about the plunger somewhere even had pics on resseting it it may have been on this site somewhere ,or a bak issue of a magazine ive piled up mountains of info on these bikes i will have to dig it out for you (im in england so there will be a delay cos of work slee etc i know your in a rush and intensly pi****d off but i need time to delve sorry but i will get bak

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