Main fuse heat

I have had my bike since 1977.I thought I knew
about everything I needed to know about it.But
this one bugs me.Earlier this year,I blew a main
fuse,first since I had a short in 1979.Thought it
was a fluke.It blew another two days later and
melted part of the fuse holder.I checked for shorts,
found none,cleaned all the connectors,installed a
new fuse box loom,and the problem went away for
over 2000 miles (a couple of months.)Tonight,wham,
it bit me again,melted part of my other fuse box.
I think I will convert the main fuse to a spade type
and try that.I have been running halogen bulbs for
a couple of years now,maybe my amp draw is more for
some reason.Anyone have the same problem?

Halogens do seem to be rated differently, or maybe just conservatively. I've noticed that older bulbs seem to reach their wattage rating when they have about 13 or 14 volts on them. But the Halogens I've measured seem to hit their wattage rating at 12 volts. This means they are exceeding their wattage rating when they operate at 13 or 14 volts. It's not a big difference, but big enough to measure.

Either way, the cause of the melted fuses is dirty connections. It's possible the copper is even corroded at the crimps. You may have to replace several inches of the wires to get to some good, clean wire to connect to.

By chance did you change from the original h-bar to a diff style, or removed/adjusted the h-bar controls?

When I swapped from the OEM h-bars on my KZ650 (wires running inside the h-bars) to Superbike h-bars (wires running externally) a few years ago, I had a similar prob with it blowing the main fuse repeatedly. It also caused the wire running to the main fuse to become incredibly hot and eventually melt. :S

When I initially ran the wiring externally, I notched the control housings with a Dremel tool to prevent from pinching the wiring against the h-bars.
Unfortunately I didn't notice that I had pushed the master cylinder and clutch perch directly against the housings = pinched wiring. :pinch:

I've since spaced the controls away from the m/c and clutch perch and fixed the shorted wiring/fried fuse box and wire, and haven't had any probs with it shorting out the main fuse anymore.

Oh yes, the old melted fuse holder trick. It's happened to me a few times. Like mentioned the cause is dirty connections between the fuse and the fuse clips. I polish the fuse clips with a q-tip and aluminum polish till they are bright brass color, then you know you have a good clean connection. Even then the fuse will run warm, but not too warm. I prayed every time I was riding at night on a pitch black road in the middle of nowhere this would not happen, because you lose your lights and all. Dangerous as heck on top of a nuisance.

I have cleaned about every connection I can find.
Since the heat is at the fuse,it is either a short
that is only happening once in a while,or the fuse
connection just can't handle the amperage.I am
going to splice in a spade style fuse holder for
the main fuse eliminating it from the box and try
that.Those seem to be the only style available at
gas stations any more anyway.One time I made it
home with a chewing gum wrapper wrapped around the
blown fuse.

If your fuse is hot, there is no question the problem is the fuse clips. A short would simply blow the fuse instantly, not cause it to heat up. Have you polished the clips like I mentioned? If so, time for a different fuse block.

I had a very similar problem. It started blowing main fuses one right after another. I couldn't find a short. I cleaned all the connectors with a Dremel tool, including the fuse clips and coated them with dielectric grease. It ran fine for a hundred miles or so, then blew another one. This time I noticed heat damage on the the fuse box, and the fuse was hot. I replaced the fuse box with a blade type, and... no more hot or blown fuses.

What brand did you use?A blade type fuse box
sounds good.Could you elaborate?

tjettim wrote:

What brand did you use?A blade type fuse box
sounds good.Could you elaborate?

Check the thread link below, it has all the install and part# details with pics.

KZ650 blade fusebox conversion

This is the same type a good portion of us (myself included) have swapped in, and it's well worth the time and small amount of money spent.

Thankyou.