'81 Kz750 blowing fuses like no tomorrow.

My '81 Kz750 blew the main fuse a couple weeks ago, I replaced it, it blew out this weekend, replaced it again, and it blew out as I was riding it down the road. Any ideas on the cause? I doubt the cold weather would cause it and I have yet to take apart the housing the check the quality of connections.

Also, I haven't had the money to upgrade to the blade style fuses, so I'm still using the glass tubes.

Many thanks!
Koki

Sounds like it's time to open up a bunch of connectors and clean them up, check for loose or dirty grounds and clean battery connections. Something is pulling more amps than it's supposed to and that is very often a bad connection.

The blade fuses are indeed a good upgrade and easy to do if you have solder, gun and flux, and some heat shrink tube.

I'd try this method of troubleshooting:

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. Just 1, not both!

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.

13. If your wiring is routed through the handlebars, check for signs of rubbing through the insulation, especially where the wiring emerges out of the bars.

I had the same problem a month or two ago (81 KZ1000 CSR), turned out to be a short as the tail light wiring had a section where the wire was exposed, just needed to be wrapped up.

If it's the same fuse I was blowing, it's got your ignition and taillight/blinker assembly on it. First thing I'd do is start looking under the rear fender for bare wire. Pay special attention to where it comes through the fender at either end as these are the most likely culprits.

if it's going, then fine, then blows again, it's likely because a bare section of wire is exposed and every time it hits the frame it's grounding out and burning your fuse.

Have you got the wiring diagram for your bike? If so just trace what elements are connected to the fuse that's blowing and check those sections of wire. As I mentioned though, given the similarity in our bikes, I'd be willing to bet it's in your tail light assembly. A good test as long as you're willing to use hand signals for awhile is lift the seat, follow the wires coming from the fender and they'll connect to a wiring harness. Unplug this harness disconnecting the tail light assembly, your brake light and flashers will no longer work so you'll have to use hand signs. Ride around for awhile, if the fuse doesn't blow you know that's where the problem is and just need to trace those wires. If the fuse continues to blow, check elsewhere.

Good luck