front brake help

[fbmbmx]

Hello everyone, Just got myself a new bike a k4 600 with r1 calipers and the standard master cylinder. I brake seems a little under powered but the lever feels lovely and solid. I cleaned the calipers by and bled the hole system with no luck. Now the strange part when i bled any part of the system and locked of the bleed nipple i had to pump the lever around 5 times until i got any pressure in the system, This even happened when bleeding the master :s. Ill explain again because its so strange, Open bleed nipple and pull in lever to pass fluid through, Close nipple and release lever then i would be able to pull the lever back to the bar around 3 times until pressure was built up and the lever feels great. Ideas please people because i'm lost.
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Suzuki gsxr 600-2003

[MickC]

In the Master cylinder there is a tiny hole that can get blocked, it's the return not the main feed, but it's usually close to the main feed hole. Also are the plunger seals in good condition?
And is the Master cylinder powerful enough to operate the callipers? (you can't usually change the calipers without looking at the master cylinder, some 'pump' at different rates)
As an after thought are brake piston seals in good condition?
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Previous: CG125,XS250 (converted to 400),Z250A, GPZ550, Norton Commando, XS500, 78 Laverda Jota, GPZ1100,Harris bonneville, XV750 (mono shock),TR1

[fbmbmx]

The pistons seem great but i will have a look for the return hole, will i have to strip anything to get to it ?
Thanks
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Suzuki gsxr 600-2003

[Kickstart]

Hi

Weak (dead feeling?) brakes with little lever travel is a sign of having a mismatched master cylinder and calipers, with the m/c piston bore too large (or the ratio of distance from the lever pivot point to your fingers / to the piston).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[MickC]

It's below the reservoir, but it is most likely that the master cylinder is no use to the calipers
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XX XXXx
Previous: CG125,XS250 (converted to 400),Z250A, GPZ550, Norton Commando, XS500, 78 Laverda Jota, GPZ1100,Harris bonneville, XV750 (mono shock),TR1

[fbmbmx]

can anyone reccomend a master cylinder then? i have heard only good things about the brembo 19 or somthing ?
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Suzuki gsxr 600-2003

[DrDonnyBrago]

[Kickstart]

[Souleh]

Does sound like the MC isnt big enough for the calipers.

Those are the yellow spot calipers? Meant to be a good job too.

Id say either get an R1 MC or if youre feeling fancy then get a brembo or accossato.

[Kickstart]

[fbmbmx]

yeah i get it (goes and looks on the bay for a r1 master, do you know if the lines will match up and could i use my lever?
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Suzuki gsxr 600-2003

[Kickstart]

Hi

Possibly the lines will match up, but the lever is probably quite different.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing