82 750k front brake overheat and lock up

[wlg3000]

The front brake was never great since I got it, the rear brake had more stopping power. The previous owner put a steel brake line on it. I've rebuilt the caliper and replaced the pads with sintered ones but within like 5 mins of using the brakes I guess they build pressure without relieving it and they drag and overheat and lock up in the span of a few minutes? And even now they dont feel like they have the stopping power they should. I cleaned the MC but I'm guessing it needs a rebuild. I just wanted to see if anyone has had the same problem and fixed it.

 

[Bo82CB]

Make sure that when you release brake lever, brake fluid goes back to the reservoir. This is achieved through your master cyl. piston travel.

 

[mrtwowheel]

Make sure that when you release brake lever, brake fluid goes back to the reservoir. This is achieved through your master cyl. piston travel.

And , fluid returning to the reservoir comes in at a tiny hole at the floor of the res. that can get blocked.

 

[Janek]

Kupiłem motocykl CB750 K8 w zeszłym roku w listopadzie, sprowadzony z USA. Klocki hamulcowe również były zatarte – ktoś tak jeździł i nie zwracał na to uwagi. Płyn hamulcowy był zżelowany.
Czyszczenie klocków nie pomogło. Problem leżał w cylindrze głównym.
Niepotrzebnie wydałem pieniądze na zestaw naprawczy do cylindra głównego, ponieważ i to nie pomogło. Problem rozwiązała dopiero wymiana całego cylindra głównego.

 

[SenseAmidMadness]

The front brake was never great since I got it, the rear brake had more stopping power. The previous owner put a steel brake line on it. I've rebuilt the caliper and replaced the pads with sintered ones but within like 5 mins of using the brakes I guess they build pressure without relieving it and they drag and overheat and lock up in the span of a few minutes? And even now they dont feel like they have the stopping power they should. I cleaned the MC but I'm guessing it needs a rebuild. I just wanted to see if anyone has had the same problem and fixed it.

Typically I'd say the rubber line collapsed inside, but because it's been replaced your theory of the master cylinder being clogged up matches my best guess. The return hole can often get blocked with gunk if the brake fluid has not been changed on schedule.

MC rebuild kits aren't expensive, especially compared to the massive surgeries you need if your front brake locks up on you suddenly...I'd just order one and rebuild it.