braking caliper on stock pump?

15 replies to this topic
  • OlaGB

Posted February 03, 2006 - 06:22 AM


how firm should the stock pump feel with the braking kaliper..?

I have been bleeding air out of the system in every way i know and not know of, and still i can pull the brake lever into the handlebars without problems...

The brakes works ok, alot better than stock, and engages somewhere around the middle of the lever travel, but i thought it should be a little heavy to squeeze the lever all the way to the bars??

Is this common, and will not be better without changing pump, or is this a sign for still being air in the system?

  • Indy_WR450

Posted February 03, 2006 - 10:40 AM


You are due for a complete fluid flush. Get a $25. vacuum pump bleeder MityVac at auto parts store. New bottle of DOT 4 and within 20 minutes you will have new brakes! Fluid gets contaminated over time so a pure flush is best. :thumbsup:


  • OlaGB

Posted February 03, 2006 - 11:45 AM


So the brake lever should be a little hard to fully squeese into the bars then?

  • Indy_WR450

Posted February 03, 2006 - 12:27 PM


Oh Yes. I have a SS braided line and mine stops half way to the bar when pulled hard. The stock one should take a lot of effort to go to the bar. :thumbsup:

  • RCannon

Posted February 03, 2006 - 02:25 PM


Try using tape, a tiedown, a zip tye ...whatever. Pull the brake lever in. Leave it depressed by using the tape or zip tye. Check it tomorrow morning and you will have a completly different feel. This really works.

Should that fail, the mastercylinder is very east to rebuild. The rebuild kits from the Honda CR's (99 and newer) work much better and are 1/2 of the cost that Yamaha charges.

  • Indy_WR450

Posted February 03, 2006 - 03:17 PM


I doubt very much that your master needs rebuilding! Just completely flush and bleed. If you dont want to buy a vacuum bleeder at least unbolt the caliper and brake line so that gravity makes a straight run down to the bleed screw! :thumbsup:

  • OlaGB

Posted February 03, 2006 - 11:26 PM


The caliper is brand new.
I have been bleeding air out horisontal, vertical, upside down, straight line, bending the line and every other way in between.. I`ve run over 2 litres of brake fluid through the system now.. I also had a motorcycle mechanic to come by to help me (friend of mine) but this was the worst he had ever seen.. Sadly they didnt have a tool like indy refered to here.. :thumbsup:

I THINK the air is around the pistons on the "back side" of the caliper, since the pistons on the bleed screw side are the ones that moves the most.. Perhaps it has nothing to do with this at all though..

  • OlaGB

Posted February 03, 2006 - 11:28 PM


oops you meant master cyl, not caliper hehe.. my bad..

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  • Brettv

Posted February 04, 2006 - 12:19 AM


yeah ive got the same problem mate, i can pull my lever to the bars, so far i have
- new SS front cr routed line
- master cylinder kit
- new fluid
- bled everyway in the world
nothing has worked

  • Indy_WR450

Posted February 04, 2006 - 05:59 AM


You need to understand that a $25.00 vacuum bleeder works so quick that trapped air bubbles dont have a chance of staying in any hidden spots. Its like flushing your toilet! Just keep pouring in the master resevoir while someone controls the bleeder screw! :thumbsup:

  • OlaGB

Posted February 04, 2006 - 07:25 AM


I will try to get me one of those then :thumbsup:

  • RCannon

Posted February 04, 2006 - 08:03 AM


The only reason I was thinking about a rebuild is because he said it was brand new. If it sat without fluid in it the seals may have taken a dump.

  • OlaGB

Posted February 07, 2006 - 09:44 PM


i tried a vacum bleeder yesterday, without solving any of my problems..

Still thinking that the Braking caliper is so much bigger than the stock, that the master cyl is`nt big enough to get a firm feel..

When i let the bike stay overnight, and then test the brake lever, its exactly the same on the first (and second/third etc) press the day after.. In a car, you often get a softer pedal at your first press, then it gets harder on the next, if it`s air in the system.. My bike is the same if i press 1 or 20 times..

  • Indy_WR450

Posted February 08, 2006 - 04:51 AM


What diameter are the pistons on the new caliper and are they 4 active pistons design or 2? :thumbsup:

  • OlaGB

Posted February 08, 2006 - 06:23 AM


What diameter are the pistons on the new caliper and are they 4 active pistons design or 2? :thumbsup:

Not shure of the piston size, but its a 4 piston caliper..

Braking came with a brand new 4 pot caliper this year, but i`ve got the old type..

  • Indy_WR450

Posted February 08, 2006 - 07:37 AM


If you are using a 4 live piston design like this Brembo road bike unit:

Posted Image

As you say you may need a larger master piston with at least a 19mm diameter like this Brembo unit to get the volume to move 4 pistons:

Posted Image

Brembo recommends a 2 piston 28 to 34 mm diameter caliper for super motard.

See Brembo web site for more info:


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