I have a 1982 Honda CM 125, and recently what seems to be the rear brake light is sticking. Using the front brake will not make it stick, but as soon as I use the rear brake it does. At first I thought this could be the switch on the brake pedal - but if you give the bike a good shake the brake light will disengage. So could this be a faulty connection? Any help with repair would be spectacular! :)
I'm not sure on an old Honda if the rear brake is manual or hydraulic. No matter, first look for a switch near the brake pedal/lever, it should be easy to spot as it looks like the neutral start switch on the clutch pedal of a manual transmission car. If there's not one then there is a hydraulic brake line pressure switch somewhere. Since you say shaking the bike disengages the brake lite I'd bet the Honda has a manual switch in the brake line linkage.
Start at the brake foot pedal, follow the line off that lever that has a string and look for an adjusting nut. It could be you can adjust it. The fact that it stays on suggests to me it is not faulty but just needs an adjustment. cables and things stretch out with age, that is why honda has adjustment options on things that need to be adjusted. If it is the switch, I have cleaned them and made them work again. If you have a handy friend , ask for help.
The plastic housing on those rear brake switches tend to wear a bit and start sticking. Clean, adjust and give it a shot of lube such as WD-40.
I have had the same problem. Angered me for days until I realized its really simple. Look down by your foot brake lever. You'll see this cylinder looking thing with a nut on the top and a nut on the bottom. All you need to do is find 2 wrenches for each nut. Unscrew each nut then that will move the cylinder up ad down. It mostly likely will take a couple of times to get it right. You will have to tighten the 2 nuts at different places every time to test it. You'll figure it out.
The switch may need adjusting. The rear of the brake pedal pulls a long spring which activates the brake light switch. The switch is pressed into a fitting on the frame. The switch has an adjustment nut on it. The adjustment nut is the part that is pressed into the frame fitting.
