Question about 2003 Yamaha YZ 125

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Front brake master cylinder wont pump fluid

Hi, the front master cylinder off my 1990 yamaha yz 125 does not pump fluid when the lever is squeezed. I have detatched the hose to see if ithe fluid comes out when I squeeze the lever. Can I fix this?

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  • lisagalva Jun 27, 2009

    Thank you. Will a master cylinder off another yz 125 of a different year fit. Are they all universal fittings?



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Yes, you can buy a master cylinder rebuild kit. If you can't find a rebuild kit the whole thing can also be replaced.

Posted on Jun 27, 2009

  • Dick
    Dick Jun 27, 2009

    Have a look at this parts microfiche from Ron Ayers. The link shows you all the part numbers for every piece of the master cylinder, including the rebuild kit. If you search for the part number 3SP-25870-01-00 you can see what years used the same number.



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I have a 89 gsx600f Suzuki the front brakes lock up ,any suggestions

Hi Nichole:
Not good! Locking front brake leads to crashes. MUST FIX!
I would start with a master cylinder check.
- Remove brake line at slave cylinder. Hold end over container, and squeeze brake lever. Fluid should come out, and brake lever should return when released. Do this several times to flush the old brake fluid out of the master cylinder, and top up and repeat.

If the master cylinder appears to be working correctly I would then proceed to the slave cylinders. If they are gummed up, have corrosion, or are impeded by dust, they may not be retracting properly.
Service should include:
- Remove front calipers, dismantle, clean
- Remove slave cylinders, dismantle, clean, Inspect for pitting or corrosioin, re-seal
- Obviously, this requires draining the entire system so once re-assembled, bleed, top up fluid level, and test.
You may want to give your local mechanic or dealer a call to get a price estimate for a brake service. Then decide if you want to attack it yourself.
Hope this helps.

Oct 20, 2015 | Suzuki Motorcycles

1 Answer

Cant get front tire back on 2011 yamaha ttr 125 le motorcycle how to loosen front break pads to put tire back on

Hi, great bike! take two flat blade screwdrivers; place 1 on top of pads, in between the pads,and the other opposite the first screwdriver then gently flex the screwdrivers sideways. You are squeezing the brake fluid back into the master cylinder on the handlebar. do it gently. you should now have enough room to slide the disc back into place and put the axle in. Happy riding.

Mar 12, 2014 | 2003 Yamaha TT-R 125 LE

1 Answer

Just tried back bleeding the front brake on my 1990 yamaha yz 125. The fluid stops where the hose meets the master cylinder and will not go into the cylinder. Then when i try the brake there is a tiny bit...

Can it be air inside that cannot escape something must be unmounted or turn loose maybe otherwise it will not fill ?

Its like so its must be deflate of air thats locked

Dec 03, 2011 | Yamaha YZ 125 Motorcycles

1 Answer

Do I need a new part or is this a regular problem with these bike?

If there is no hose or restriction, the cylinder will do that. There is no check valve or other device to prevent backflow - it has to backflow otherwise the brakes would not release. If it is not producing pressure then it may need to be either cleaned or rebuilt. These are simple to rebuild.

Oct 25, 2011 | 2003 Yamaha YZ 125

2 Answers

I am having a problem bleeding the front brake with the standard method on a Yamaha XT 125, 2005 model, can anyone help?

I may need a bit more clarification, but I am assuming the lever is 'spongy'?
The simplist thing to do first is to tie the front brake lever back (ie make it stay on) using a zip tie. Leave this overnight/24 hours and it will allow the trapped air to rise.
Failing this, you can bleed the brake in reverse. Get a large syringe (ebay/chemist) and some pipe that fits over the bleed nipple and the syringe. Remove the master cylinder cover and **** out (use the syringe) the brake fluid. Now fill the syringe with fresh brake fluid and connect to the bleed nipple on the caliper. Open the bleed nipple and slowly push the syringe in, to force the fluid up to the reservoir. Be careful that the fluid doesent come out of the reservoir and splash on your paint work. Lock the bleed nipple up whilst still slowly forcing the fluid in. This normally works.

Sep 09, 2010 | 2007 Yamaha XT 125 X

1 Answer

How to replace front brake line for 03 fatboy (flstfi) and bleed the front brakes system?

Just take your old line off and replace it with the new line. Be careful because the brake fluid will damage your paint if it's DOT 4. One you have replaced the brake line, fill the master cylinder with the proper brake fluid. Open the bleeder valve and let gravity do it thing. Usually once the fluid starts to flow out of the bleeder valve, all the air is gone as well.

But if the brake lever still feels spongy or no brake at all, first bleed the master cylinder. Squeeze the hand lever and hold it while you loosen the union bolt on the end of the master cylinder. Once the pressure bleeds off, close the valve and repeat the process until you get no air bubbles. Then, move down to the brake caliper and do the same thing until you get no air and a full brake lever. You must do it in this order exactly. Squeeze the lever, open the valve, close the valve, let go of the lever. Do not allow the master cylinder to run dry during the bleeding process.

Good Luck

Aug 31, 2010 | 2003 Harley Davidson FLSTF Fat boy

1 Answer

How to refill brake fluid on front brake after replacing brake line?

The best way to completely bleed a system is to back bleed. This is done by pumping brake fluid from the bleeder fitting backwards from the caliper to the master cylinder. You can use an all metal pump can or an irrigation syringe and a clear piece of tubing to do this. Just make sure you remove and clean the bleeder fitting first. This method works like a champ.

If you don't want to backbleed, put a clear tube on the bleeder fitting - make the tube long enough that it will go from the bleeder fitting up an inch or two, then bend down into a container. Fill the master cylinder and open the bleeder, then just start pumping the lever. It may be unproductive at first but eventually if your master cylinder is good, it will start to pump fluid. No need to close the bleeder and build pressure then crack the bleeder - just pump the lever. Just make sure to keep the master cylinder full. Pump slowly and completely.

I hope this helped!

Mar 06, 2010 | 2003 Yamaha YZ 125

1 Answer

Front brake lever spongy,not operating brake ebs hh brake pads fitted.

Gravity bleed front brake. no lever pumping. Looden cap on master cylinder, front wheen straight ahead, open bleeder and watch for air being expelled. When only fluid is coming out, close bleeder. Expect the front pads totake a few miles to seat, They will improve as they wear in. Good Luck / be safe.

Jul 01, 2009 | 2004 Yamaha TDM 900

1 Answer

Would a front master cylinder off a different bike fit my yz 125?

the only way to tell is to match them up with out knowing exactly what year they both are its hard to tell but the change every couple of years

Jun 27, 2009 | 2003 Yamaha YZ 125

1 Answer

04 Yamaha Yz 125- Rear brake Master cylinder

Are you bleeding it by gravity (flowing down from resevior thru caliper) or forcing the fluid up thru the caliper to the resevior. The latter will get more air out in less time. Simple cheap pump kits are available at you auto dealer and u can use it on your other vehicles.

May 14, 2009 | 2004 Yamaha YZ 125

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