I killed my cb750c... 1981.... very sad... please help.

Ok, so I was riding the other night and a concerned driver flagged me down and let me know my rear lights weren't working. The brake light and the turn signals worked, just the riding light was out.

So, today I decided to take a look at it. Everything looked good on the outside, so I checked the fuse box (the one on the handlebars that says "Ignition Fuse")

I saw that one was broken, so i replaced it. My lights were still out. So, I removed another fuse to see if I could pinpoint where the problem was with the lights.

I pulled the 1st fuse (on the far left) and turned on the key. There was a hsssssssssssssssssssssssing sound. I reached over to turn off the key and the key itself was hot enough for a nice 2nd degree burn.

So, the bike is off. I have a burned hand and it appears the bike is dead.

Did I just destroy the ignition? Do i have a chance of resurrecting my bike? Am i the dumbest guy in the world for doing this?

Please help. It is a wonderful bike. 1981 CB750c with a slight oil leak. Very durable. Until now.

If the problem is just the ignition, can I remove it and just bypass the need for a key?

Thanks

fireballbrady

That's an interesting one. With that much heat something was definately shorted to ground. Have you checked the voltage on the battery to see if it was drained?

My first thought for the light would have simply been the bulb. If the brake light was working just not the tail it's likely one of the filaments was bad in the bulb.

At this point I would disconnect the battery, check it's voltage and check all my fuses. Replace any bad ones, make sure you have a good charge, and give her a shot. From there you would have to start doing some electrical troubleshooting. Check your chassis ground to make sure it is clean and tight. Look for any wires that have the insulation rubbed off and making contact with the frame, motor, or any other metal part.

Electrical demons are the worse.

Good Luck

fireballbrady, you have a potential mess on your hands. The hiss you heard was the short, smoking wire(s). The hot key told you where to begin your detective work. In all electrical repairs of this nature, you have several things to consider; first, what did you have before you did anything? (sometimes helps to write it down so you don't miss anything later) what did you do and in what order to the point of the electrical China Syndrome? (this order of events is important to point at where YOU affected the CS, not the original fuse issue). If, in the process of 'repair' you up-sized a fuse or worse, 'pennied' a fuse (using either a coin or chewing gum wrapper) you forced a "Smoke Test" effective but usually very expensive shortcut to the problem.
Now, having this information, you now need to begin your repair. Disconnect and remove the battery (this prevents you from 'touch testing'). Remove the fuel tank, seat and headlamp. Look for burned wires from the ignition switch wires and through the headlamp bucket (the typical wire terminus or heart in the early CBs) and then down the frame back to the taillamp. Remember that the head and tail are on with the key so the short could have pre-existed (blown fuses) but you still don't know why. Look at the biggest suspect areas. Where he harness wraps around the forks and down to the frame is a wear/pinch point. Tank saddle vs harness? Seat or battery box vs harness? rear fender insulator where the wires come out to go to the rear light pod or the pod itself?
Replacing wires is not hard, but will be the deciding mechanical act as to its future reliability. 1)replace wires with the same gauge and color. 2)use waterproof fully insulated bullet or spade connectors. 3)make your connections and then do a proper 'pull apart' test. The connectors should pull apart without ripping the wire out of the connector. 4) do a connectivity test. with a volt meter (trust me this works) hooked at each end of the circuit (ie headlamp black / switch red) the voltage should be '0' with no light. Turn your light on and the voltmeter should not read more than 0.5V or your wires/connectors are not good.
The good news is that the CB was simple. You killed the lighting circuit and that is totally repairable. Borrow a friends service manual and go to the wiring schematic section. This can be your bible in getting things right.
Most of all, don't let electrics scare you into throwing your CB away! Think positive and keep things simple. Electrical work is actually fun and very rewarding.