under pressure

[KPac]

My rear brake on my '77 750 will build up excess pressure in after riding a few miles and not release.
I'm sure this is just a clogged return.
My question is, is this problem normally in the lines, the cailper or the master cylinder?
I was going to buy a master cyl rebuild kit, but wanted a few opinions about what I should be looking at tearing apasrt first.
On a related note, my front brake light switch doesnt work. i took it apart at the bar and someone took out the little piece that moves and makes makes contact when you squeez the handle. Anyone have any experience with "universal" pressure type switches, or should I try to get a stock replacement?

[t3rmin]

I was able to clean out my front brake light switch, get all the corosion off the metal parts, pack it up with dialectric grease, reassemble, properly adjust, and it worked fine again. Make sure you're not missing any parts: there should be a flat metal U-shaped thing and a spring.

[KPac]

Make sure you're not missing any parts

I already know I AM missing parts from the front switch... but my main issue is the pressure relief on the rear brake.
Want to know if this is an issue in the lines, master cyl or the caliper.

[Iceman71]

KPac,

Start at the caliper, check first before you ride that all is mechanically fit (pads are alright, nothing is loose, rotor not warped, no leakage from around the caliper piston, flexlible lines are not kinked or split, master cylinder doesn't leak, rubber gasket under the master cyl. cap is alright, fluid is good not real dirty, foot brake lever is adjusted properly and the system functions ok - meaning in nuetral spin the rear wheel by hand, apply the brake and release...does it work as expected?)...once you've done this verify all is back together good and take it for a short ride to make the problem occur, now when the brake won't release gently open the bleeeder screw on the rear caliper..does this releive the pressure..if so then you problem is most likely the flex line or the return port to the caliper, if not the problem lies in the caliper.
I hope I have covered everything and that I am not leading you down the garden path..I am much more familiar with cars.....I trust if I am in err someone will set me right...
Just be carefull when test driving and remember to close the bleeder screww when your done (bleeding the brakes is always a good idea as well)
Hope this helps

[KPac]

when the brake won't release gently open the bleeeder screw on the rear caliper..does this releive the pressure..if so then you problem is most likely the flex line or the return port to the caliper

Thanks, this is exactly what its doing. I'll start from here

[Iceman71]

glad i could help, keep me posted
good luck