I would bleed the system and put in new fluid.

 

If your brake works well, no flattering on the handle just fill up with fluid and that's it. I would fill it up and check the level regularly, to make sure you are not losing fluid. brake pads are fine until they are completely worn down to the metal, however the recommendation is to change them when they are worn down to the bottom of the grooves.

Changing brake fluid is cheap and quick, but it's really easy to screw it up. You might end having to brake or mess up the bike with brake fluid, which harms chromed parts and generally metal if not cleaned up quickly. You could still do it, but there is absolutely no point, if you say it's not dirty and it still has the light color.

 

+1 :thumbsup:

 

I would just put dot4, but maybe I'm wrong.

 

I went to Wal-Mart's aquarium section, and bought some clear hose from them. It fits well, and snug, over the bleeder valve. Then run it into a small bottle, or container, to catch the old fluid.

Alternatively, you can use a brand new, oil pump can, to push new fluid UP the line, as opposed to sucking/pumping it down the line. Fill the pump oil can with fresh brake fluid, connect it to the end of the clear hose from the aquarium store. Pull the brake/clutch lever part way, holding it in place with a zip-tie, and then pump fluid UP the line. Be sure to prime the line with brake fluid prior to connecting it to the bleeder -- you want to avoid pushing any air into the system.

By pumping fluid UP the line, you push it in the direction air bubbles are trying to flow towards. This aids any bubbles in rising to the reservoir, as opposed to trying to push them DOWN the line, which is the opposite way they want to flow.

Honestly, I would top it off, and keep an eye on it. Why mess with it, until you know there really is a problem? Cheers!

 

If the fluid has not been replaced in the last two years, you should flush new fluid into the system. I use a MityVac to empty the reservoir, refill with fresh fluid, then bleed the fresh fluid into the slave cylinder. Do not bump the lever when the reservoir is empty.

And, DOT3 and DOT4 are compatible, even with DOT5.1 (not DOT5); some brands come labeled as both DOT3 and DOT4. The only difference is the initial boiling point.

 

I'd really like to know why they had to go and confuse everything with 4, and 5.1. They could just as easily just put IMPROVED on the DOT 3 cans and been done with. And made DOT 5 DOT A or DOT Z to really not confuse people. Or is there really something about them that makes them not truly compatible? Like can you put DOT 3 in a DOT 5.1 system and not have trouble? It really confuses me. But maybe it's my old brain.

As to the OP, I'd check the owners manual or the top of the reservoir. I personally won't mix them. That's just me and my limited knowledge of exactly what's going on with that stuff.

 

It's easy, Hog:

Keep DOT 5 separate.

The others are compatible.

Not sure what kind you have in there? Take a little out and put it in a container, and add a few drops of water. If it mixes together and stays mixed it's either DOT 3, 4, or 5.1.

If it doesn't mix together it's DOT 5

 

The demand for higher-performance brakes on sports cars created a demand for higher boiling point fluid - DOT4 was created with a new number so you didn't confuse it with DOT3. Then so-called super cars, and they needed DOT5 temperatures without the complications - DOT5.1. If you run a lower number in a system that calls for a higher number, you risk losing your brakes in an emergency stop. For most driving/riding, it really doesn't matter.

 

Ah, so we caused the issue by demanding faster and faster vehicles. That makes sense. But they could have just put the words IMPROVED on Dot 3 and then made DOT 5 DOT Z like I said before. But I guess corporate and stockholder greed for more money keeps that from happening. I like keeping things simple. It's the same with oil. Rather than just IMPROVED we now have so darn many oils that people are putting the wrong kind in all the time. Also good for bringing in more money with repairs and replacement engines. Nothing anywhere is just plain simple anymore. It is what it is.

 

If the pads are fine, should I just fill and flush the brake fluid and.....

Yes but keep in mind, when you start with new pads and a full reservoir the fluid level Will Drop as the pads wear.
If you full the reservoir while worn pads are in place, when it's time to change pads you'll need to bleed some fluid out to make 'room' for the new thicker pads.

 

On a second thought I worked quite a lot with hydraulic brake systems. When I needed to change the fluid, I always put new fluid in the reservoir and pumped the old fluid out. Filled regularly to make sure no air is pumped in. I said it's done when at the bottom only clean liquid came out. Never had any problem. Dot 2, 3, 4? No idea. I used dot 4 all the time.

Note: I'm not a mechanic, I just love to work on bikes.

P.S: If you drain the whole system to clean it, and then put new fluid, it will take a lot of time to get the air out of the system. In this case you will need to bleed also at the top, at the connection between the reservoir and the brake hose. The air gets pumped UP all the time(I guess). If you have air in the hose itself, it may never get DOWN in the caliper where the bleed screw is.

 

If you have air in the hose itself, it may never get DOWN in the caliper where the bleed screw is.

That's true, especially for motorcycle brakes. There is only a small amount of fluid movement with each lever pull, so getting the out the air high in the line and in the banjo bolt area can be tough. When flushing it's really important to make sure air isn't introduced into the system.

 

That's why I prefer to push the stuff up rather than down. Seems I just saw someone say the same thing but not sure if it's here or another site. Anyway you are going the way bubbles like to go, up, that way.

 

That depends on if you are bleeding air out or flushing old fluid. I prefer to push old fluid out the bottom when flushing. The bulk of the old fluid can be removed with a turkey baster, then the rest pushed out of the line.

 

Actually I do it both ways flushing the old out the bottom but then pushing the new up until the reservoir is full.

One can of the stuff has way more than I need so this works well for me.

 

Reverse bleeding - pushing it up from the caliper - is very effective when filling an empty system, for the reasons stated. You can still trap bubbles in the banjo fitting, if you don't first tilt the reservoir so that it is the lowest point. If there are bubbles trapped there, you can, with patience, get them out without opening the fitting.

First, tilt the reservoir, second, very slowly squeeze the lever (so not to push bubbles down the line) and hold several seconds (so any bubbles that were pushed down can float back up), third, let the lever snap back (pulling some air into the MC). Because there is so little flow, if there is much air trapped, it will take several cycles to get it out, but it will work without spilling fluid. This works a LOT faster with clutches, because the amount of fluid moving is so much greater.