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Master Cylinder or Brake Lines
- cpg
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I have new stainless steel brake lines for my '81 CSR 1000 but I haven't installed them yet and I am wondering whether or not I should also do the master cylinder at the same time. It started with my brakes being soft in the heat so I assumed, and was told, it was my old lines deteriorating even though they appear to be in pretty good visible shape and do not leak (they do have very tiny cracking and look a little weathered). From what I can see looking through the window in the MC the brake fluid is also older looking but doesn't appear to be full of moisture and is at an acceptable level. However, even today when it was only about 35 degrees F (usually a temp where the brakes are a little harder), if I kept pulling on the brake handle it would go all the way to the bar and never hit a point where it got really hard or too hard to pull further. I know it could probably use a fluid change and I'm sure the old rubber lines have some give but my thought now is that the master cylinder is also bad since the brake handle can always be pulled to the bar no matter how many times they are pumped. The calipers are in good shape and there are no leaks of any kind.
So, what do you think? Should I also do the master cylinder while I'm at it? I would hate to do new lines, pads, fluid and get the system bled only to find out my MC is shot or will be soon. Judging by how weathered it is, it must be the original and probably hasn't ever been touched. Thanks for any help or suggestions.
Current Bikes: KZ440 LTD and KZ305 CSR
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- MFolks
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The stock brake lines will expand when pressure is applied, so you're changing to the SS braided lines is a good step.
1982 GPZ1100 B2
General Dynamics/Convair 1983-1993
GLCM BGM-109 Tomahawk, AGM-129A Advanced Cruise Missile (ACM)
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- dsmking
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live fast die young.
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- martin_csr
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- cpg
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- TeK9iNe
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- What did you do!?!
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Anywho... clean up your MC anyways. Just pull all the guts on it and wash/clean them up like new.
Then hone the inside of the MC with some 0000 (4 zero) steel wool for several minutes, then wash and rinse it out repeatedly till shiney and new like.
Lubricate and reasemble things, and I guarantee this will make a big improvement in the operation and longevity of your MC - It just needs some attention!
You may need a rebuild kit if the diaphrams are damaged, but not likely. Too much $$$
Motorcycle Shop Owner/Operator
79 Kawie Z1000 LTD
81 Kawie Z1000 CSR
83 Honda VT750C A
85 Kawie GPZ900 A2
86 Zukie GS1150 EG
93 Yamie XV1100 E
Lucky to have rolled many old bikes through my doors
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- Patton
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Where the master cylinder isn't leaking, it's likely not getting a little weak, and the bore is not worn out .cpg wrote: ... new pads, SS lines, and new fluid. I initially bled the brakes then drove the bike for a while and bled them again so there is no air left in the system. However, I still have a lot a play in my brakes and I can still pull the brake handle to the bar so I'm guessing my master cylinder is getting a little weak. At this point I have several options and not sure which route to go. I could rebuild my old master cylinder but I'm not sure how effective this would be and I'm not sure whether or not the bore is also worn out....
Most probably some air remains in the system. Although it may be invisible while bleeding.
Some methods of filling and bleeding are more efficient than others at preventing introduction of air upon filling and later purging air from the system.
And clean fresh fluid should be used -- undisturbed, not roiled in any manner before using, and definitely never dropped or shaken.
Good Fortune!
1973 Z1
KZ900 LTD
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- Patton
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Good Fortune!
1973 Z1
KZ900 LTD
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- cpg
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- Patton
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Wouldn't expect dis-assembly of m/c to accomplish very much where it isn't leaking and each stroke is pushing the proper volume of fluid.cpg wrote: ... will take it apart to make sure it is all nice and clean....
Good Fortune!
1973 Z1
KZ900 LTD
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- SPARKY47
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- 1980 KZ500 B2
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As TeK says,restore the bore and generally service it.My rear mc played up and I read the same advice here which I followed, I now have rock hard brakes.
Also, the primary cup and its friend are available,the 1000 and 500 share a number of part numbers.If you need them I'll dig out the suppliers.
I recall Zpower in the UK have them.
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Location: Middle England[/b
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- cpg
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