Very little stopping power - Front Brake

Hey guys,
Front brakes seem a little mushy and don't seem to do much. This is my first bike so I thought maybe that's just how it was but a buddy of mine rode it and said they're damn near useless.

What I've done:
Bought a 16mm bore M/C
Bled brakes (didn't flush)

Don't know what else I can do, any ideas? The hydraulic hoses are stock, probably original but seem to be in good condition.

Thanks for any information.

XJ750 Midnight

 

I highly recommend replacing the brake lines if they are original. Steel braided lines will help a great deal. Also ensure there's no air in the line. My brakes are definitely not mushy, so it sounds like something is amiss.

 

I have had pads that are so hard they just would not seat in. Going to a new set of pads can make a huge difference if there a softer material and grab the rotor better.

 

+1
New pads.
Rebuild the calipers (30 year old seals are not a good thing).
Replace the 30 year old rubber brake lines with new braided lines.
And of course use new brake fluid and take your time bleeding the system.

Don't ride it again until you do. The front brake system does almost all of the work.
A rebuilt system will be good enough for modern traffic conditions, but it will not be quite as good as the system on most bikes built after the mid 90's.
You can supplement your braking by shifting into a lower gear and using the engine's compression to help slow the bike, but be careful to not lock the rear brake, or let the clutch out too fast when compression braking.

 

Any helpful links for rebuilding the calipers?

 

Yes.

http://xjbikes.com/forums/threads/another-guy-with-locked-front-brakes.12529/

http://www.xjbikes.com/forums/threads/why-you-need-to-rebuild-your-caliper-and-m-c-w-pics.41403/

ww.xjbikes.com/forums/threads/easy-brake-caliper-piston-removal-contraptioneering-1.35191/

http://www.xjbikes.com/forums/threads/why-you-need-to-replace-original-brake-lines-w-pics.41400/




Bonus material:

What I do to bleed the system. (note that I wrote this is for the XJ750 Seca, so disregard the part about all four bleed fittings (your bike only has two), and the part about using a syringe to fill the master cylinder).

1. get a large syringe from a farm store and about a foot of vinyl tubing (you can also use a 2-stroke oil mixing syringe).

2. Cut 6" of tubing and attach that to the end of the syringe. Remove the Syringe plunger. You now have a funnel to fill the master cylinder with.

3. Break loose all four bleed fittings (be sure to put down cat litter or drip pans).

4. Tie the brake lever to the grip.

5. Fill the master cylinder and syringe.

6. Wait overnight (or at least a few hours)

7. You should now see brake fluid coming out. Close the bleeders, and untie the brake lever.

8. Bleed the brakes as normal, starting with the anti-dive bleeders, then the brake caliper bleeders. Remove the funnel.

9. You aren't done yet. There will still be some air in the system. The next step cures that, no matter what mehtod you use to fill and bleed the system.

10. Use a vibratory sander (no sanding pad) and slowly run it along the brake lines, calipers, and distribution block from bottom to top. This will move any remaining air bubbles up into the master cylinder. Tap (or vibrate) the master cylinder to get the air bubbles to come out of the return hole. This process can also be done with a box-end wrench or other simmilar tool, and tapping the calipers and lines (it just takes longer).

11. Do one final bleed normally, just to be certain that the calipers are fully bled.

12. Use a flashlight to check the fuid level in the master cylinder. It should be below the fill neck. Unfortunately there is no dip-stick or sight glass on this master cylinder, so unless you empty it and measure out the fluid you will need to just eyeball it. If the fluid level is too high the brakes can hydrolock and not release.

And when you're bleeding the system normally, be darn sure to close the bleed fitting before the brake lever is pulled all the way, otherwise air will get sucked back into the fitting.

 

Another way to bleed the system after rebuilding the calipers and installing new lines is to use the syringe K-Moe referred to along with the vinyl tubing and reverse bleed the brakes. Attach the vinyl hose to the syringe nipple, draw in some brake fluid, loosen on of the bleed fitting and slip the vinyl hos on to the fitting and using the syringe push fluid into the caliper slowly until you get fluid coming into the master cylinder. Close the bleed fitting and do the same thing to the other caliper being careful to go slowly. When the fluid level in the master cylinder begins to rise close the bleed fitting. At that point I tapped on the brake lever several times to get the final small air bubbles out, and then bled the brakes as usual. The complete job took about 15 minutes for my XJ700. Maybe I was lucky but it sure worked well for me.

 

A third way to do it is using a vacuum pump, attach it to one bleeder at a time and just suck the air out, really easy.
Just make sure you fill the master cylinder before it gets dry, otherwise you'll got start over again.

 

I use a vac pump (sometimes), but it still doesn't always get all of the air bubbles out. This is particularly true on the 750's because of the internal shape of the caliper passages.

 

It worked really good on my 750 seca, was no problem at all.

 

I will envy you from afar. Most times after a full brake rebuild it's not very easy to bleed that system fully. I'd have loved it if a vacuum bleed had gotten all of the air bubbles out from mine.

 

Really i had no problems with it. But before i tried it in the regular way wich wasn't that fun....

 

I'll try vacuum again the next time I have to bleed them.

 

dont forget to take apart the slides on the brakes too i had seized slides and the brakes wernt even touching the discs you have to take them apart and grease them up pistons on the inside and replace rubber boots if torn they let the whole calliper adjust side to side slightly.... one way of seeing this is press the brakes and look down the lines of the disk and see if there is any gaps between any pads and disk
...

 

^ and polish them if they are corroded. Replace them if they are worn enough to prevent them from moving freely.

 

This. Had the same issue. One piston was off kilter. When I got done, it was like night and day.

 

Definately follow all this good advice posted herein. Also, buy a master cylinder rebuild kit. Replace the master cylinder reservoir cover as well. Do not ride until you have resolved your braking issue.
Carefully inspect the piston outside diameter and the caliper bore for pitting and corrosion.
I replaced the two OEM hoses with a single one from HEL Performance.

 

This is what the 550 Seca plunger looked like.....that bike also had very little front brake stopping power! Interesting thing was, the rear brake shoes were brand spanking new EBC.
Like I had said earlier, I did a complete hydraulic rebuild, that bike now has exceptional "feel" and stopping power...don't skimp....do the whole shootin' match, you won't be disappointed!

 

Oh, and this is what my Venture's rear master looked like....it also had poor stopping power (on the Yamaha XVZ12 Venture, the front right and rear calipers are linked, so I was basically stopping a 900+ pound bike with one caliper)