Main 30A fuse melting

Here's a problem I thought I'd never see. My bike is an 82, I bought with 2,550 miles on it a few years back, up to about 10k now. Last fall she kept stopping dead and I'd discover that the main fuse was bad. I'd replace it roadside and continue on my way, but this happened every 50-100 miles. Finally I decided to take a careful look at the blown fuses (they were all still in the bottom of my tool kit pan). I discovered that the element in the fuse was not blown or melted but the solder holding the element into each metal end cap had melted. How is this? Resistive heating I concluded. I looked at the fuse holder clips and being 28 years old, they were pretty dark with oxidation. I took a small piece of emery cloth and rolled it up the size of a fuse, put it into the clips and shoved it back and forth and polished the clips clean. I put a little good ol' Vaseline on the clips, put in a new fuse and it's been fine ever since.
Just FYI!
Good luck

Dirty oxidized connections will make you pull your hair out chasing electrical gremlins

To reduce this chance on my bike, I use some Brasso metal polish on a cotton swab followed by an application of De-oxit contact cleaner/preservative.

The website www.deoxit.com list it's uses. It can be purchased at Radio Shack stores in the U.S. or any electronic supply stores.

Another option is to replace the old glass fuses with a modern fuse box that uses the new blade type fuses. Been meaning to do that to my bike, but haven't gotten around to it. Right now I just carry a bunch of extra fuses with me all the time.

This is a common problem on these old bikes. As mentioned before you just have to do a very good cleaning on the fuse connections. I just bought a very nice BLADE type fuse box at the auto supply store to update to the newer fuses.

I had this exact same problem on my '82 KZ750H3. Same melted solder on the 30 amp fuse! Drove me crazy.

The problem is that the old glass fuses can get an intermitten connection in the fuse holding clamps from corrosion and dirt, and that is a form of resistance that heats them way up. Blade fuses use no solder-it's just a continous piece of metal all the way through. They also physically run cooler (so I've heard).

Then, as riverside has mentioned, I replaced the box with a blade type fuse box (Radio Shack has a nice one for 5 fuses). You'll also need some push-on blade connectors for the wiring ends (or better yet, solder them on).

The problem never came back!

In my experiences with melting wires or a main fuse, a lot of the time it's attributed to either a corroded faulty ground, or corroded male/female connectors. Inside the headlight bucket is a notorious location for mositure. Bad connections are fairly easy to spot. Many times the connectors will melt and look physically distorted, and many times you can see "bluish gunk" this is a tell tale sign of a suspect connection.