Blown Main 20 Amp Fuse - '82 KZ550 LTD

My bike has intermittently been blowing the main 20 amp fuse in the fuse block (on an '82 KZ550 with stock everything, there is one 20 amp and two 10 amp fuses). In a year and a half, I've only blown two...until yesterday, when it blew for the third time. I replaced the fuse, and as soon as I turned the key on, it blew again...and again...and again. I fiddled with the wiring harness under the instruments, replaced the fuse, and started it up and ran it just fine for five minutes. Shut it off, went inside. Came out the next day, turned the key...and it blew again.

Obviously, I have a problem. In examining the visible wiring, I can see that someone prior to me had been into the wires under the instruments - there's electrical tape there. However, I can't tell what was worked on, or whether that may have failed again.

Ideas?

The Dreaded Shorting/Intermittent Electrical Problem!


Here is the most basic method I know(Taken from www.kzrider.com by member Patton)

1. Charge your battery and have it load tested if you can. The floating ball hydrometer can be used to check the specific gravity of the charged cells in the battery.

2. Disconnect the Black lead from the (-) Battery terminal... or Red from the (+) Battery terminal, it does not matter which one.

3. Connect one of the following test setups in series with the Battery terminal and lead:
3.1 A 12 V light bulb,
3.2 A 12 V test light,
3.3 A 12 V test buzzer or,
3.4 A 12 V horn... you get the idea.

4. With the Ignition Switch OFF, go through your harness and wiggle the wires while looking/listening for the test setup to go on/start buzzing.

5.With the Ignition Switch ON, repeat the test except this time the looking/listening for the test setup to go off/stop buzzing.

6. Be prepared to open the Ignition switch and check/test for solder joint failure and or circuit board micro breaks (don't ask how I know this ).

7. Be prepared to pull the wires out of the Head Light to test for failures at or near the grommet.

8. Be prepared to open the harness at or near the Steering Neck for failures. This is where wires tend to exhibit fatigue due to repetitive movement.

9. Be prepared to open the left and right switch gear to search for rust and or broken parts. CAUTION: watch out for flying springs, ball bearings and stuff. Do indoors on White sheet (again don't ask ).

10. Be prepared to follow the heavy gauge wire from the Starter Solenoid (Relay) to the starter for bare wire exposure. Especially near bends and grommets.

11. If you can reproduce the fault symptom your are pretty much home free. Be prepare to find and repair/replace any internal wire breaks, insulation break downs, exposed wires, rubber grommet failures, etc. Often, shrink tubing will solve the problem temporarily until something better can be done.

12. I use a very good electrical contact cleaner/preservative called De-oxit made by Caig Labs in San Diego Ca. Their website is www.deoxit.com It can be purchased at Radio Shack and any other electronic supply store. I use it on all of my motorcycle’s electrical connectors , in my home entertainment center’s stereo patch cords and cordless phones charging cradles.