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Discussion Starter #1
A while ago I changed my front brake line to a Stainless line and ever since then the lever has felt spongy. The bike stops fine, but my friend has the exact setup as I do, and his lever takes one finger to stop.

I've bled the system several times over, and still nothing has changed.

Any ideas of what else could be going on?
 

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you might need some teflon tape at the bleeder screw threads... it might be allowing some air in. Or, possibly while bleeding, you are releasing the lever before shutting the bleed screw and allowing air to suck back in.
 

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Bleed it at the upper banjo bolt on the master cylinder. Just hold a rag around and crack the bolt loose for a second. Also try tapping the lever really fast but gently with the cover off and watch for bubbles. Good luck!
 

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+1

while squeezing the lever in........

Bleed it at the upper banjo bolt on the master cylinder. Just hold a rag around and crack the bolt loose for a second. Also try tapping the lever really fast but gently with the cover off and watch for bubbles. Good luck!
 

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If your pads are not new and over half worn that can increase lever travel. One way to know if this is the cause is if after the spongy feel- it firms up and holds before going to the bar.
 

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Discussion Starter #7
The only thing listed that I haven't done was the teflon tape and trying to bleed from the master cylinder banjo bolt.

Argh!:damn:
 

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this should solve your problem...

as your pads wear down, the pistons in your caliper must move further and further out... If they have not been cleaned in a while, the seals around the pistons can stick to the pistons, and will flex with the pistons as you use the brakes... everytime you let off the brakes, the seals "pull back" on the pistons and pull them away from the pads / rotor. This means, everytime you pull the lever, it has to move the piston out 1/16 or 1/8" before theres any contact piston to pad to rotor.

pull the caliper off, remove the pads, clean the pistons (pump them out a few squeezes with them off the rotor and then clean the dirty ring off them), then replace the pads, and dont pry the pistons back open... instead, with the pads in place, pump the lever untill you literally have to tap the caliper w/ pads OVER the brake rotor... i.e. the pads are dragging a bit. This way, when you hit your brakes, the pads are just barely touching already, and you have instant response, and when you let off, the come to "rest" still barely dragging the rotor (not enough to notice).


This is an old trick we do to our street and race bikes. It might be a bit tough to do on a supermoto where you have to install the inside pad after installing the caliper (like my YZ) but others should work easily.

It ends up giving you instant rock hard brakes, with little lever travel. Of course, this all only works if you've bled them well to start with.
 

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Don't know if you fixed it already but, was it spongy like that before the pads? What kind of brake fluid are you using now?
Also, you might try cracking the bleeder screw just a weeee bit with the reservoir cover off. were fluid doesn't come out of the bleeder as long as you don't have the lever pulled. Leave it for a few hours or overnight tighten and bleed as normal. Sometimes the bubbles just take a bit to work their way out.

The other option is buy a 27 dollar mighty vac and do it the easy way.
 

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I'd make sure that the master cylinder is the highest point in the system, if it isn't, tape down the line so it never rises above the master...any high points will trap air bubbles. tap the line for a bit once high point(s) are lowered. then bleed at the master first, so you're not forcing bubble down the brake line. then bleed at the caliper like normal. Yamaha and car and bike manufacturers don't use thread sealant or tape on brakes or hydraulics because it can end up in the system and block orifices which could be dangerous, costly, or both.
 

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Discussion Starter #11
Don't know if you fixed it already but, was it spongy like that before the pads? What kind of brake fluid are you using now?
Also, you might try cracking the bleeder screw just a weeee bit with the reservoir cover off. were fluid doesn't come out of the bleeder as long as you don't have the lever pulled. Leave it for a few hours or overnight tighten and bleed as normal. Sometimes the bubbles just take a bit to work their way out.

The other option is buy a 27 dollar mighty vac and do it the easy way.

Come to think of it, even before the Stainless line it did seem a bit squishy. I've put stainless lines on pretty much every bike I've had and it always made a huge difference.

I use Castrol Dot 4 Synthetic Brake Fluid. I originally had some Prestone Dot 4, but immediately changed it.

I do need to look into a Mighty Vac though.
 

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I think the power bleeder is on sale at Harbor Freight.

Some times rapping on the line with a screw driver handle will help the bubbles work their way up the line.


.
 

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Come to think of it, even before the Stainless line it did seem a bit squishy. I've put stainless lines on pretty much every bike I've had and it always made a huge difference.

I use Castrol Dot 4 Synthetic Brake Fluid. I originally had some Prestone Dot 4, but immediately changed it.

I do need to look into a Mighty Vac though.
The Mighty Vac(Power bleeder) is a life saver and the castrol is a really good choice too I've used it in many bikes. As a suggestion you might try motul 600 or ATE superblue as an alternative next time. I know it's probably a street bike but you will get better feel and feed back from those fluids. imo

Hopefully you saw this too and it works great. We sometimes forget the simple stuff. Try this first.
http://www.supermotojunkie.com/showthread.php?t=56542
 
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