A forum for owners of Yamaha TTR250 trail and enduro bikes!

steelprunes · Newbie

front brake

Lin · Senior Member

Pretty much any mc and lever will not work. Fit ONLY the correct TTR master cylinder and lever. Hydraulic brake cylinders are sized to provide specific ratios and pressures, not to mention safe and reliable mounting. Overhaul kits for the front calliper are available and fit a new set of pads. Unless you REALLY know what you are doing, messing around fitting odd-ball brake parts is messing around with your future good health.

-- Edited by Lin on Sunday 6th of November 2011 06:07:33 PM

mockadash · Member

Hi m8s ..

my Japanese camel brakes,  but the handle comes up to the fist. Will it be on the top pump or the bottom pump ??

(sorry my bad english)

regards

Moo · Senior Member

Air in the brake lines? You may need to bleed the brakes

TTRfan · Super Guru

Are there any signs of brake fluid leaking out from the master cylinder (on the handlebars) or the caliper (on the wheel)? Or is the level of the brake fluid staying the same when viewed through the sight glass?

Brain

mossproof · Super Guru

The front brake fluid is held in the square reservoir that the lever is fitted to. 2 small screws hold the lid on and can be difficult to remove. The front brakes are often very hard to bleed (remove all the air from the system) I recommend take the brake caliper off the wheel and hold it level with the handlebars. Put something between the brake pads to stop them pushing together. Put a small tube over the bleed screw on the caliper to control the direction the fluid squirts! Loosen the bleed screw and pump the lever many times. Get help to keep the fluid level high in the reservoir. When your hand gets tired, on the last pump, hold the lever in and tighten the bleed screw. With luck you will have moved any air bubbles along the tube and out through the bleed screw!
Good luck,
Simon.

JOHNYBOY · Super Guru

same as simon says but once you have some sort of a brake pull the lever & tie it to the handlebars with small amount of pressure leave it over night you will see a difference in the morning you can use a cable tie or lace clip to do this

mockadash · Member

Brake fluid does not appear in any place ....
stable level above the minimum ..
my doubt is if I should change the interior of any of the pumps (upper or lower or both) ...
Saturday I will try to bleed ..
the plate Inside the reservoir works up close to the membrane or underneath the two little holes?

Moo · Senior Member

The problem with tieing back the lever, it works if the reservoir is the highest point. But on most trail bikes, the brake hose is the highest point, so air will gather there.

I find an easy method is to use a big syringe to push brake fluid through the bleed nipple, and empty the reservoir with a 2nd syringe. Works really effectively as it pushes all the air out and can be bought for a few quid off eBay.

mossproof · Super Guru

IF there are no leaks at the caliper end, and the pads, pins and sliders all move freely, then the problem is most likely either air in the system, the hose has a weak spot and is expanding under pressure, or the master cylinder seals (the handlebar end) are past their best.
If there are any seized parts in the caliper, it will flex the pins rather than sliding properly, so when you release the lever it just flexes back again.

If the hose has a weak spot you should be able to see it expanding when you pump the lever.

If the master cylinder seal is no good, I would expect the lever to creep when you hold it under pressure (lever moves towards the handlebar gradually when you keep pressure on) There would not be any leaks visible.

Very old brake pads can also cause this symptom, and so can new ones until they are worn-in to the shape of the disc.

The plate can be pushed low - all it does is stop fluid squirting out in your eye when you are pumping the lever with the lid off!

First step is to give the system a good bleed with fresh fluid. Moo's system is a good one. I have also heard people use a liquid soap dispenser pump to suck fluid through the bleed screw. If you can set it up to remove any high points in the hose where air might collect, so much the better.

Good luck. I hate brake fluid!

Simon.