78 KZ650SR Electrical Death - First time problem

Today, I go to get my '78 KZ650SR inspected - starts fine as always, 10 miles to inspection, no problem once warmed up. Passed inspection, lights, horn, brakes, kill switch, went to leave and no start. No lights on tree or anything.

I look everything over, check fuses and notice main looks a little different, less shiny. Change fuse, still no electric. Pull and replace fuse, start up, ride away. 2 miles from home, accelerating from a stop sign, electrical death again. Check fuses again, little fuse box is HOT. Fuses good, but can see melting around fuse holders connected to white and white/red wires.

No restart, push bike 2 miles home - first time ever.

I can't complain, first time she's faied me ever.

She had 8k original miles, Dyna Coils, Dyna electronic ignition (has had both for 5 years). KZ is in GREAT shape and rarely ridden (since I picked up a 2003 Z1000.)

Before I start removing and replacing stuff, any ideas?

Thanks!!

Welcome to the forum Dave. A 2 mile push is not an easy thing. I've done it after blowing a main fuse and I can sympathise.

Blowing the main fuse is usually due to a short to ground. First time for me I had to trace all the wires and I found the problem inside the headlight shell. MFolks describes a method to track down an intermittent short in this post
kzrider.com/index.php?option=com_kunena&...ew&catid=4&id=301853

You mentioned that the fuse box was hot. Are your fuses the long glass type ? I have heard of the brass fuse holders for the glass fuses becoming corroded and hot and causing fuses to blow or melt. I might be worth checking this angle out and cleaning the contacts........or you could do like I and a lot of others on here did and get rid of the old style fuse box and go to the blade style fuses and fuse holders.

Thanks for the reply! The fuses are the glass type. It's odd that they did not blow, but, the brass holders melted THEIR holders in the fuse box.

I'll check closer for corrosion which could have lead to toe issue.

-Dave

Stick around and I'm sure there will be many people more knowledgeable than me come along with better advice..

I'm working on switching from the older glass tubed fuses and holders to the more recent ones seen in cars and bikes.

www.waytekwire.com sells the ATM(mini fuse)size holders for the automotive "Blade" style. I'd imagine it would be available from www.delcity.net and www.wiringproducts.com too.

It's just a matter of figuring out where to mount it as with the cover installed,it's a little bit taller than the stock glass tubed one is.

Another common place for these bikes to short is in the handlebar wiring underneath the throttle/starter/kill switch controls. I just fixed a dead short on mine (kept blowing the main fuse every time I switched the key on) and it took me 2 days to track down the short underneath the throttle pod. A cramped wire developed a crack in the insulation and was shorting against the handlebar. Be patient, these problems can be a frustrating PITA to figure out.

Dave wrote:

Thanks for the reply! The fuses are the glass type. It's odd that they did not blow, but, the brass holders melted THEIR holders in the fuse box.

The only way that's possible is if the brass connection to th fuse is resistive enough that the current flowing through that resistance heated it up enough to melt the wire. Sounds like the fuse box may be the culprit.

If looing to update your fuse holder and switch to the flatblade fuses try this product. Installation was easy. It comes in both 4 & 6 way. Great for also placing spare fuses in unused slots.

cgi.ebay.com/ebaymotors/ATC-ATO-6-way-Ra...7C39%3A1%7C72%3A1171

Very common problem. There are two things that cause a fuse to fail and they are easy to tell the difference.
The first is the classic "short". This is a wire rubbed through shorting to ground. In this case the fuse "blows". Usually blown black inside throughout the glass. This is not what you have.
The second is the overheating fuse that melts the surrounding plastic, fuse opens up because the end melted. The fuse may not even look bad. This is exactly what you have.
The best thing to do is probably go to a different type of fuse like some guys have done using the blade fuses, but I prefer to leave stock and not cut up wiring. I've had this same problem countless times, just a month ago actually. What happens is the fuse clips get corroded, contact to the fuse is weak and the fuse will get red hot. I get a metal polish like Simichrome and a q-tip and polish away at the fuse clips until they are bright and shiney again. This takes a little while to do, but works just fine.

I'll give that a try.... I had put maybe 5 miles on her this year and corrosion may have set in. I can see a little, but it may be enough.

I also took apart the kill switch and headlight housing - no issues in either location.

I'll let you know when i find the "gremlin" but please keep the recommendations coming!!

-Dave

SUCCESS!!! 99% sure!

Cleaned off semi-corroded contacts which didn't look THAT bad, read out replacement fuse (cooked but looked ok) read out old fuse (looked a little off, but had good resistance), started right up.

Gonna add some fine sandpaper and a few 20A fuses to the toolkit!

Next test is a long ride - crossing my fingers!

The original glass tubed fuses are the AGX type, 1" long, but the more common AGC fuse is 1 1/4" long. Some AGC fuses may fit the older style holder but not without some work.

Most good auto parts stores can get the AGX fuses and some even have them on hand.