advice on front brake master cylinder

[rkubik]

It works OK, but it feels a bit like the brakes in an old car. When the lever is squeezed, it initially presses hard, then you can feel it go down so the lever pulls closer to the bar. When pumped, the action hardens up again, then softens.

Bike 1982 GS650L, single front disc. Original brake line, looks OK but very repeat very slight oozing of brake fluid around banjo bolt.

Installed a rebuild kit, first an aftermarket one which seemeded dodgy and then a Suzuki one which looked more like the original parts. Gave the cylinder bore a very light wet-sanding with oiled wet/dry sandpaper.

Worked better for while, but it's back to its old ways. So how to eliminate the problem?
- install braided lines (planning to do that anyway for reliability, once the money is saved up)
- replace banjo bolt crush washers to get better seal?
- somewhat more agressive sanding on the cylinder bore? I've heard this may not be a wise idea on anodized aluminum bores, even though it's OK on cast iron ones in cars.
- replace the master cylinder with something newer, say from a GS500 or the '90s Kats? (the original master cylinder is discontinued). I do have Superbike bars on it now, so a brake cylinder less angled might be nice.

Any advice welcome, thanks in advance.

[chef1366]

If you have fluid coming out then probably air coming in. Replace copper crush washer. Plus the older those rubber brake lines get the more they flex.

[txironhead]

Got a Ninja master on my 750, had a Virago master on my Shadow. I'd go with a newer M/C, just make sure it came off of a bike with a single front disc. You want approximately the same bore as stock. Plus, you eliminate the very outdated factory brake light switch and have a newer, cheaper, more reliable switch, the only mod is soldering in some new connectors. Just make sure to write down what the master came off of in case you ever have to buy a rebuild kit for it. I picked mine up, along with the lines, lever, switch and six-pot Nissin calipers for a dual-disc for a whopping $12 off of Ebay. Still trying to figure out how to mount the Nissins on my GS750EX........

New washers are a must any time brake parts are worked on, you can buy a 10-pack cheap. All they are are nickle-plated copper washers.

I'd also go with the braided steel lines like you mentioned. I prefer Russell lines, they're universal, last forever and you can get tons of different banjo fittings, stainless, adonized, etc. Dennis Kirk is pretty cheap on them, you may find them cheaper elsewhere.

New master cylinder, braided lines, new washers and I'd go ahead and rebuild the calipers and check/replace the pads while I'm there. Just make sure you don't go over the handlebars on the first test run when the bike stops better than it did new!

[fgh]

Those are classic symptoms of a bad master cylinder. Your plans and chef1366 are right on. When sanding the cylinder all you need is to do get it clean. If there are pits or scratches that won't come out its history. To clean it get a piece of dowel about a 1/4 of the bore. Cut a slot in the end and insert two pieces of fine emory cloth into it. Abrasive side out of course. Load the dowel into a drill, spray a little WD-40 on the paper and run it up and down the bore until its clean. When assembling the MC remember the rubber seal that goes in after the spring has to have the larger diameter inserted first. LOL

[rkubik]

Got a Ninja master on my 750, had a Virago master on my Shadow.

So the banjo bolt connection is prety much universal? I like this idea.

[txironhead]

So the banjo bolt connection is prety much universal? I like this idea.

It is on metrics, at least the ones I've tried. Of course, Harley masters won't fit the handlebars. Just make sure that the master is for 7/8" handlebars, some of the newer metrics are using 1" now. And make sure that it's made for the number of discs you have.

[Billy Ricks]

Make sure the master comes with the banjo bolt. Suzuki uses something a bit different than the rest.

[txironhead]

That's true, I forgot I had to use the Kawasaki bolt on the Ninja master. Good call!