Second time the main fuse blew

[James Gray]

Hello,
I was out on a short ride the other day on a 1978 CB750A that recently put on the road.
Riding along at about 30 mph the bike just died.  The fuse wasn't blown, but the solder that was holding the filament in was melted and resting inside the tube.

I figured it was a bad fuse (kind of old) so I replaced it and didn't think anything of it.  Today I was out on another short ride and at 25mph through a housing development and the bike died again.

This time I had a spare fuse with me and replaced it, then got the bike home. I was using a 32v 15amp fuse today when it happened, and that is what I got home with. (didn't need the neighbor to help push this time.)

The left side of the fuse holder has a bit of carbon on it but otherwise everything looks okay.

Where do I start troubleshooting?

Thanks,
James

[hondamatic...@gmail.com]

I would study the wiring in an around the fuse that is an issue.  Follow it through out the bike.  Somewhere there is a dead short (hot wire coming to ground).

[John Yakel]

Ok, there was a recall on your bike way back when.  This is totally "normal" for a 1978...the wire to the main fuse is too thin and also the chromatic cating on the fuse holder breaks down causing excess heat.  There is a board for hondamatics on yahoo - the administrator also known as hondaman sells replacement parts....I will post a link to his site:

 

http://forums.sohc4.net/ 

 

...more info here than any man should need....good luck.

[John Yakel]

http://sohc4shop.com/catalog/index.php

 

Here is the hondaman's website - he knows these bikes like the back of his hand.

[Dave Snow]

I invested a $100 and bought a new fuse block thats updated and comes with all new wiring from cyclex but lots of options and price ranges available. Try Amazon or even JCW. Worth the investment to not get left on the side of the road in the middle of bfe! Cruise it safely my friends!