Replacing and/or bleeding brake lines. Nothing short of pulling a bank of carburetors causes the average rider more distress.
Steel braided brake lines are one of the best bang-for-the-buck mods you can do for your motorcycle. Maybe the very best mod a guy can do for a around a hundred bucks. Steel lines provide better braking feel and increased stopping power because the lines don't expand under pressure like the cheap rubber OEM ones do.
Now that you've decided to make the leap, go ahead and buy your line kits from wherever you like. You will also need brake fluid and you might want to obtain some Speedbleeders.
As for the whole debate on what brake fluid to use, many people get excited about synthetic DOT 5.1; the selling point on this stuff is that it resists boiling better than DOT 4 and is less "hygroscopic" too - which means it tends to absorb less moisture over time than DOT 4.
However, unless you're talking about a dedicated track bike, its not as economical. It's typically much more costly than DOT 4 and cannot be mixed with anything else if you're low on fluid and in a pinch.
Fresh DOT 4, changed out once a year in the spring, will serve you just fine and will cost you less.
Another useful tool to bleed brakes is the basic Mityvac Brake Bleeding Kit, the cheap plastic one that sells lots of places for $25 or $30.
Don't get intimidated by the relatively lengthy instruction manual that comes with the Mityvac. In fact, you just as well toss it in the trash. This tool is a simple vacuum pump, nothing tricky about it. Affix the clear vinyl tubing to the pump with the inline capture cup attached and you're ready to go.
Let's start with the front brake lines, shall we?
- Put your bike on front and rear work stands, or a rear stand at least. You want it level and sitting on a solid, stable platform.
- Remove your windscreen and set it aside. It's easier to work on the front of the bike w/o the screen on, and this way you avoid mucking it up with a spilled drip of brake fluid (more on that later). Put some old towels on top of your instrument cluster, fairing, and fuel tank too.
- You should have some plastic clip-type fasteners which hold the factory lines to the back of the fender. Remove those so the midsection of the lines are free.
- The first thing you'll use the pump for is sucking out the bulk fluid from the reservoir cup. Unscrew and remove the plastic cover, insert the free end of the vinyl tubing, and pump to your heart's content. Easy as pie.
- Next you'll want to drape some more towels on the bottom half of your front wheel because you will still have fluid in the line, and when you unbolt it from the caliper, it's going to dribble some. (Note: at the risk of insult, the hex-head fasteners which attach the lines to the master cylinder and calipers are called banjo bolts, so that's what I'll refer to them as from here on out.) Just have a jar or bottle handy so you can put the leaking free end of the stock rubber line inside to catch the majority of the draining fluid.
- A word on working with brake fluid: don't flip out if you get a drop on your fork, caliper, wheel or other painted surface. Stay calm, wipe it off with a dry paper towel (more absorbent than a cloth towel) and you'll be fine. You might want to clean the now dry spot with another paper towel and some Honda Spray Cleaner & Polish (to this day, I love Honda chems!) if you're really worried about it. The point is, people talk about brake fluid as if it's nitroglycerin or something sure to ruin your bike the instant it touches anything painted. Not true. Be careful, wipe up spills, and you'll be fine.
- Okay, once the majority of the fluid in the line has drained, unbolt the banjo at the master cylinder up top on the right clip-on. Have a paper towel ready to capture any drips from the top of the line. Carefully thread the line down through the fairing and out the bottom of the bike. You'll be tossing it, the OEM banjo bolts, and all used crush washers (new ones come with your Galfer kit).
- Get the new lines ready. The front kit is a two line affair with a long and a short line. Take a look at the back of the package - it'll tell you where to place the new crush washers, how many to use, etc. (basically at each and every 'joint'). The short line is the right side which will go against the master; the left line rides on top of it. Bolt everything up, make sure the lines aren't binding on anything at full lock, then torque to 12 to 15 ft-lbs.
- Unscrew and remove the stock bleeder nipples from both the right and left calipers. Again, you may get a drip. Just have a paper towel handy, this is not the end of the world. Replace the stock bleeders with the new Speedbleeders you bought. No need to seal the threads with Teflon tape or wheel bearing grease as the SB's come with thread sealant already applied. Tighten them down with a small wrench, but don't overtighten.
- Now you're going to attach the Mityvac to the left caliper's SB via the clear vinyl tubing. Set it down and get your bottle of DOT 4. Carefully pour it into the reservoir cup, almost all the way to the top (just leave enough room that it doesn't spill if you jiggle the bike a bit). Unscrew the SB 1/4 to 1/2 a turn. Begin pumping the Mityvac. You'll see fluid begin to disappear from the cup. Now you're beginning to prime the lines.
- At first you'll be sucking only air and you'll have to stop pumping from time to time so you can stand up and pour more DOT 4 into the cup (you don't want to let it get sucked dry because that means you've drawn air into the system and you'll be starting over).
- Eventually (it really doesn't take too long), you'll see fresh brake fluid coming out of the SB, through the clear tubing, and into the catch cup attached to the Mityvac. Keep pumping and pouring until you get mostly clean fluid coming through without big gaps of air pockets (small bubbles will remain, but don't fret, we'll take care of them in a few minutes).
- By now you might want to unscrew the Mity's catch cup and dump the fluid into another container. Snug up the SB on the left side. Go around the bike and prime the right line in the same manner described above. Once you get mostly clean fluid coming through, you've got both front lines primed and you're ready for the final bleed.
- At this point, you're done with the pump. You can remove it, leaving yourself a length of clear tubing to attach to the SB's and the catch cup at the end. I like to go back to the left side caliper and start the final bleed there because it's the longest line, but I have no scientific reason to support why I do this. I think you could begin on either side and have it work out just fine.
- Again, you'll want to back out your SB about a 1/4 to 1/2 turn. Attach your tubing and catch cup. Make sure you've got sufficient fluid inside the res. Give the brake lever a full squeeze, slow and firm, all the way to the bar. Then release, keeping an eye on your fluid level to make sure you don't run dry as you go. Repeat above as necessary.
- You should see movement in the fluid and a gradual reduction in not only the number of bubbles coming out the SB, but also in the size of them as well.
If you've done things correctly, you should be pushing virtually unblemished, virgin DOT 4 through the lines and out the SB in very short order, just a number of pulls on the lever.
You might need your husband, wife, S.O. or roomie here at the end, because I like to close the SB about mid-stroke on the brake lever just to make sure the line fluid is under pressure when the escape route is sealed off. (You can simply tighten the SB after your last pull of the lever and be okay, however. The internal check-valve is what prevents air getting into the system.)
Now go over to the other side of the bike and repeat the final bleed process.
Once you're done up front, you pretty much follow the same steps to replace, prime, and bleed the rear line.
The final thing I like to do is use a nylon tie to hold back the front brake lever with the bike on its side stand and bars locked to the left. This places the master cylinder as high as you can get it. Take the plastic handle end of a screwdriver and gently rap the calipers, banjo bolts, and lines from top to bottom. By the next morning, any teeny-tiny bubbles which might have evaded your expert bleeding adventures should have, in theory, escaped up and into the res.