Fuse keeps blowing - 1981 KZ750 LTD

Apologies for the long post.

I am trying to solve an electrical issue with my 1981 Kawasaki KZ750 LTD. The bike has been running fine for the last few months, but for the last few days I have been blowing up fuses at random moment, bringing the bike to a halt. While there isn't any obvious factors leading to the fuse blowing (use of turn signals, break light..etc.. or leaning the bike a certain way) - the problem seems to occur the most while I decelerate. At time the bike will run 2 miles before the fuse blow, sometime 40 miles... again no consistency there. The bike starts and shifts through the gear without any issues.

When the bike is running, the fuse stays intact if I use electricals (headlight, turns signals, break light - or combination of). Similarly while the bike was running, I have tried to move the harness about to see what area would pop the fuse and nothing happened. Same leaning the bike or turning the handlebars both side.

The only difference I can think between the time the bike did not have this issue and starting to blow fuse is that I rode the bike out in the rain for about 20 miles one evening. The bike ran fine in the rain, and ran fine the day after.

So far....

I have check most of the electrical harness to look for frayed cables or anything that may cause a short. I have found a few and small area which may have caused an issue and taped those with electrical tape.

I have check the connection to the few electrical components and buttons and nothing seems unusual

There is quite a few wires going in and out my headlight, which I thought might be an area to check because of the movement and possible rubbing. Didn't find anything there.

Having done all of that - the bike still blows fuse and am a bit at loss to what might be the issue. Here below are the only other thing I can think about:

- the bike battery is old and doesn't hold a charge very well ? Maybe due for a change? Could this be the issue?

- the same fuse (10A) keeps on blowing - there are two 10A fuse in the fuse box. Should I just raise the Amp ? I am worried this would just mask the issue - and the bike has always run well on this setup.

Any ideas welcome!

I had a similar problem with my 83 KZ1100 LTD.
I bought a new fuse block and while preparing to install it I discovered what the problem actually was.
One of the fuses had heated to the point where the solder had actually melted out of one end.
It ran down the fuse blades and puddled under that post.
It was shorting out the system under the fuse block.
Take the fuse block loose.
Pry the plastic protective cover off the bottom and clean the melted solder away from the fuse blade block.
Worked like a charm. Still using the original fuse block and no more blown fuses.
Good luck

Does your KZ1100 have fuse blades? The KZ750 uses fuse glass tubes. That being said, I will follow your suggestion and inspect the fuse block more thoroughly. Thanks!

I was referring to the brass clips that the fuses slide in between. Not sure what the proper term is. Hope it helps! Riding season is upon us here in Tennessee.

DO NOT put in fuses that are rated for higher amps! The original fuses are sized to protect the wiring and are normally sized based on the size of the wires they protect. The wires and the fuses are sized to handle the load the wires carry. If you put in a fuse that is rated for higher amps the wiring can (and probably will) burn up before the fuse blows. Ed

Thanks for the advice on the fuse. Does anyone have any thoughts regarding the battery and how likely it is to cause the issue?

Which of the 10A fuses is blowing? One is for the headlight (goes to the reserve lighting device, blue/white to blue wire), the other is for the dash lights and the taillight (brown/white to red/blue).

You need a strong, healthy battery for the engine to start and run the way it should, but I really doubt if it is causing your fuse problem. Does the fuse holder clamp the fuse firmly? Are the clamps dirty or corroded? Have you looked carefully at where the wires come into the fuse block? The wiring diagram in the factory service manual will identify which circuits are protected by that fuse. The ownwer's manual might, too. That will narrow yor search. A simple, inexpensive volt/Ohm/amp meter will be a huge help in tracking down the culprit. Some dedicated electrical contact cleaner like Deoxit D5, some tiny brass brushes and some small picks for carefully cleaning all the connectors in those circuits, and a bucketload of patience should restor the system to factory spec.

Thanks for all the replies - I'll try to do an in-depth clean of the fuse holders and clipsand see if this makes any changes. Will report back.

I'm still betting on the melted fuse solder under the fuse holders. It was the same 10A fuse that was blowing on mine.

If not your fuse block,maybe in the harness somewhere a wire's plastic coating (insulation) in shorting out. I would take off the fuel tank and seat. Then put on ignition and start at tail light wires and wiggle them . Continue slowly up the harness if the fuse blows , you have it. Inspection of wires as you go. Up into head light bucket were most are jammed together.
If nothing, then go to switches.
Let us know please if you succeed.

Had the same problem, went through atleast 30 fuses on the side of the road.
I switched to mordern blade fuses and never blew a fuse again.