Xj550 Seca Front Brake Issues

Hey Everyone,

I have a 1981 xj550 seca. The front brakes don't work well and I'm not sure if it's because that's how it was originally. Could anyone help me out?

• I have replaced the brake lines and bled the front brakes. (got them from Chacal)
• I have the big bore MC part number HCP1808WO (got it from Chacal)
• The front caliper was rebuilt and brakes were replaced and the rotor is in good shape.

The bike stops but needs a very hard squeeze to be effective.
I'm considering a few options to improve that:

1. Replacing the front forks from another bike (xj650 turbo?) to have dual disk brakes
2. Getting better single brakes like EBC or anything(read on xj forums that they were good)

I will be getting steel brake lines after the cafe/brat build is complete at the end of winter ( I haven't started yet)

What could be the issue? I will appreciate any help or pointers.

 

Maybe your new brake blocks haven't bedded in to the rotor yet.
Some light sanding of the blocks or just some more riding and hard braking should make that better.

 

Thanks for responding. I've been riding this entire summer so they should be settled in I suppose. Any other ideas?

 

There is a adjustment screw that determines the amount the plunger on the master cylinder operates. Makes sure that's adjusted correctly.
It sounds like you still have residual air in your system. It's common with bikes of this era.
An easy way to expell all the left over air in your system is to pump the lever about a dozen times then secure the lever back all the way with a zip-tie. Make sure the handlebars are turned so the m/c is as high as possible, to the left. Leave the lever secured overnight. This allows all the micro bubbles in the system to naturally rise to atomosphere. I can almost guarantee you'll find a noticeable improvement to your brake lever feel and operation.
Plan on replacing your lines, as you mentioned, to further improve your front brake system operation. They swell when the brake is operated and rob stopping ability by doing so. If you look at the lines on your bike there is a date of manufacture on them. 1980 was the date on my 1982 bike brake lines. I replaced them and the bike stops scarey fast now.

 

Why did you get a master cylinder with a larger bore? That's usually only done when adding a second brake caliper.
Did you add a second caliper to the system?
I ask because you only mention rebuilding one caliper.

If your bike has only one brake caliper, and the big bore master cylinder, that's why you need to squeeze harder for the brake to work.

 

I was planning to add a second caliper and a second rotor during the winter, but it's not there at the moment.

 

Thanks a lot for your response. I will try those steps out.

 

I would advise against riding with the setup that you currently have.
The ratio of the master cylinder size to the single caliper does not provide enough mechanical advanage for you to make an emergency stop.
No amount of adjustment or bleeding will correct that.

 

X2 what @k-moe said, I did same thing and used a larger MC with a single caliper and it was horrible to stop, not much lever travel and had to squeeze hard.

 

I need to confess;
my front brake configuration is a dual disc type with the 5/8" bore M/C. So my above advice may not be a good fix for your issue with your set up. K-moe knows his shit with these bikes and consistently offers sound advice.
If your running the correct sized M/C then my advice stands as the way to get more lever response.

 

Where is this adjustment screw of which you speak!
I'm pulling right to the grip so want to ensure bleed is good and will be trying this technique..

Never mind!... doh! on the handle!