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Having problems with my 2000 GSXR 600 Brakes. I want to replace the master cylinder with something else. Wondering if anyone knows if you can use on from another bike or does it have to be from a gsxr 600. Cheers.

Why do you want to replace the master cylinder? What problems are you having with the brakes... there may be an easier fix. It is possible to order an oem master cylinder from almost anywhere.

Alternately you can bolt on a whole new lever right hand assembly and it will have a new master cylinder, one from any bike would technically work, but you want to get one with the same bore and stroke ideally.

Okay, just because I'm silly like this, when you say master cylinder do you mean the thing that stores the extra brake fluid, or the actual master cylinder which is the part that is pressed by the brake lever to actually make the brakes activate down at the calipers. I ask because this seems to be something that is confused a lot. I had it wrong until I had to learn it.

If you want to replace the reservoir (the part that holds extra brake fluid) then it's relatively simple to do... assuming it's a remote holder - a line is run from the reservoir to the grip, and then from the grip down to the brake caliper.

Just undo the line from the old one and attach the new one. You may need to bleed your brakes afterwards to get rid of air bubbles. And you want to be really careful to not to get any brake fluid on your paint or anything else.

Now if you want to replace the actual master cylinder. You probably need to replace the entire lever assembly... but here's the thing: There is no real reason to replace a master cylinder unless your current one is worn out (takes a VERY long time). Because the only difference is the bore and stroke of the cylinder. Now it can improve or soften braking, but you can get adjustable levers for cheaper, or you can fit braided brake lines that look and work better if you're looking to improve performance.



This is a reservoir for a gsxr, I'll try to find a better picture of some in general later.

my bad, I meant the actually leaver and assembly. I have installed hel braided lines, cleaned the calipers and installed new seals and done a pucker blead job. The leaver still does not feel at all right and over time seems to get worse. Also if I am able to buy say a used r1 leaver it would be great as they have a bleed at the leaver end of the system

What do you mean by "getting worse" and "doesn't feel right"?

The brakes do not have the stopping power I would like and I can not get the leaver to be 'firm' enough. Right after I bleed the system it feels great and I can not get the leaver to the bar with one hand. After a couple of days it is 'soft' I know their is no leakes lower down on the system. If I put a newer system on with say a larger piston (if it will fit) would this solve both problems?

cheers for the help

After a bleed it's good. But you lose pressure over time.... and there's no brake fluid coming out anywhere?

Go pump the lever a couple of times and see if it firms up. If it does this means you've still got air bubbles trapped somewhere. Bleed the far caliper first, then the near one. Be really really careful in the bleeding.

If you just installed new lines and the problem appeared I think it's REALLY likely that you've just got some air trapped in there.

Otherwise it's possible you've got a leak past the master cylinder... meaning you could just buy the new parts and slot them into the existing bore and it should be okay. You'll need new circlips, oil seals and a piston. Though it is possible that you've got a bore worn out.

In that case you could probably just bolt on any lever assembly and rebleed the lines. However, you want to find one with as close as possible to the same bore and stroke as your existing master cylinder. Because what happens if the one you have on there is bigger - brakes start way sooner. If it's a smaller displacement the brakes engage later. The shop manuals will tell you what the bore and stroke should be.

Did you use new crush washers when you installed the lines? And are you sure the bolts are correctly torqued?

wafu46 wrote:The brakes do not have the stopping power I would like and I can not get the leaver to be 'firm' enough. Right after I bleed the system it feels great and I can not get the leaver to the bar with one hand. After a couple of days it is 'soft' I know their is no leakes lower down on the system. If I put a newer system on with say a larger piston (if it will fit) would this solve both problems?

cheers for the help

It's possible to have an air bubble in the system. Of course, that should manifiest itself quickly by having spoingy brakes from the start, but just keep it in mind as a possibility. When you bleed, be sure to tap the caliper, lines and MC/banjo bolt. It's easy for air bubble to get trapped at an intersection.

I don't think a larger piston will solve a leak problem. There's a break or interference somewhere, you just have to find it rather than throwing new parts at it. That can get expensive.

Did you use new washers on the calipers and the MC connection? If not, you should.

During the course of a bleed an air bubble that is still trapped can be compressed to almost nothing as you pump the lever repeatedly. Once the bike is allowed to sit for a bit the brake fluid moves back into the reservoir and the air bubble expands.

So the brakes will feel great right after you finish the bleed, but slowly get worse as the brake fluid "settles out."

It's likely the brakes just need to be bled a bit more.

Other then that, in some cases re-using crush washers on the banjo bolts can mean that air will flow in, but brake fluid won't get out. So that's worth thinking about as well.