When the brake fluid isn't changed often enough it forms a hard, crusty "varnish" on every part the fluid touches. My master cylinder did the exact same thing. I thought my return spring was broken.

When you rebuild the m/c you'll need to build a tool consisting of a 4" rod with a small 1x6" strip of 400 grit emery wrapped around the end. You place the rod in your drill motor and use it like a hone. You're not trying to remove metal, so keep it moving. You should end up with a bright shiny bore over the entire length.

If the bike is new to you, don't take chances. Replace the brake fluid in BOTH systems !!

Also use this opportunity to replace all the flexible hoses with those generally called "stainless steel". This will improve the brake operation tremendously, and remove a possible future failure point.

Thanks for the info. I thought it was the mc needing a rebuild. Any lead on the SS brake lines? Im thinking running two separate lines from the master cylinder then one to each caliper.

Thanks for the info. I thought it was the mc needing a rebuild. Any lead on the SS brake lines? Im thinking running two separate lines from the master cylinder then one to each caliper.

See this thread RIGHT HERE....

That was on a 1979 with ATE. The procedure is the same for Brembo, but the end "fittings" change at the caliper end. For the front you want the hoses with the 45 degree cant on 1 end. The m/c ends gets AN3 to M10x1.00 straight fittings. The front caliper ends probably get AN3 to banjo fittings.

The best solutions run the hose all the way from the m/c to the caliper with no intervening joints or couplings. The 45 degree end helps the hose connect to the m/c with no steel line, and clear the underside of the fuel tank.

I got everything needed at Race Part Solutions.

🙂

FYI, I'm doing a complete brake job, front and rear. Thanks again.

As a follow up: totally went through the brake system. The last owner must have cleaned them the day it was new (1983) and never touched them again! Corrosion in the handlebar lever, thick goo in the calipers! About a 1/2 tube of "never seize" I think, between the pads and calipers! What a mess!

Rebuilt everything, works like new.

Thanks for the advice

Eric

People just don't realize what a tremendous mess old brake fluid can make of a good brake system. They assume that just because it works in their cars for 5 or 6 years that their motorcycle will be OK. It's not. The bits on a motorcycle are far more exposed to water and adverse elements than any car.

Glad to hear you got it working. I know it's been a huge effort. However, you'll feel much safer on your bike with good brakes.