Topic: Blowing fuses!!

[KC3]

Hi all,

I have a problem. I am blowing my "main" fuse on my '76 cb550f. I have a stock-type of headlight; no turn signals; one LED tail/stop light and two incandescent tail/stop lights. That is all I am running for lights. I think it has something to do with my light setup, but I am not sure. This has happened randomly before I added my tail lights, so I don't know what to think.
 
That being said, as I understand it, to blow a 15A main fuse, I must have more than 15A of current going through that fuse. The only cause for that would be a short, right?? Could it be that my battery is just undercharged and the generator is overcompensating?? Or is it more probably a short somewhere? If so, where do I start looking? Any ideas?

-KC

[bollingball]

Are you saying you have 3 tail lights and 3 stop lights?
Ken

[scottly]

Check/clean your fuse holder; a dirty connection there can cause the fuse to fail from over-heating. Is the fuse "blowing" in the middle of the element, or melting at one end? Blowing in the middle would indicate an over-load, or short, while melting at the end would indicate a faulty fuse holder...

[Danno]

like scottly says clean and verify everything especially in the headlight bucket and make sure the main ground from the battery to the frame is good and not rotten the 550 hates oxidized wire connections as does  many other bikes

[KC3]

Thanks for the tips. I'll give them a try this evening and post back with any results. Yeah, I have three lights on the back end. All three function as tail and stop lights.

The fuses are blowing in the middle and the plastic holder got so hot that it melted. The solder behind the fuse box even melted a bit..! I think its a short...I'll check the wires in the headlight bucket tonight.

Thanks
-KC

[bollingball]

The only cause for that would be a short, right??
Or to much of a load.

You may want to get this if your is melted to much. It is truly plug and play.

http://sohc4shop.com/catalog/product_info.php?cPath=23&products_id=48
How many fuses are there on a 76 550? I don't have a print for that model. Can someone post one or a link to one Thanks in advance.
Ken

[KC3]

That's what I'm thinking too. I am a bit confused though, because I thought if the tail circuit was overloaded then the tail fuse would blow...right?? Same with the headlight..but the main is blowing...! I don't know..it's probably something simple..Also..I forgot to mention that I installed a new fuse and it wouldn't work until I slid the fuse back and forth in the holder to make a good connection...that makes me suspicious about the fuse block. On that note, thanks for the info about the spade style block..I plan on picking one up asap. I believe my fuse block only has three fuses: MAIN, TAIL, and HEAD. The other two slots are spares.

Cheers,
KC

[Mooshie]

The only cause for that would be a short, right??
Or to much of a load.

You may want to get this if your is melted to much. It is truly plug and play.

http://sohc4shop.com/catalog/product_info.php?cPath=23&products_id=48
How many fuses are there on a 76 550? I don't have a print for that model. Can someone post one or a link to one Thanks in advance.
Ken

I put that ATC fuse box (from the link) on my 550 and it was truly simple.  Even a woman can do it. 

[weekend_junkie]

What he said.

I had a 550 with fuse problem too.  Replace that fuse block for something with blade fuses.  Simply, easy, 100% effective.

[Mooshie]

What he said.

I had a 550 with fuse problem too.  Replace that fuse block for something with blade fuses.  Simply, easy, 100% effective.

I actually am a girl....

[weekend_junkie]

What he said.

I had a 550 with fuse problem too.  Replace that fuse block for something with blade fuses.  Simply, easy, 100% effective.

I actually am a girl....

Fine, what she said.

Here's a link to a 3 circuit fuse block, but I'm sure I've seen them cheaper.

http://www.easternbeaver.com/Main/Products/Fuseboxes/3_Circuit/3_circuit.html

[Duke McDukiedook]

Look for a short somewhere or a bad ground or corroded terminals to fuse. Swap in with a newer bladed fuse would be highly recommended.

By the by, Indiana requires turn signals for all bikes manufactured 1/1/56. I would assume that means front and rear.

[TwoTired]

If the fuse box has melted, solder melted, it is not due to over current, but rather the fuse clips have become oxidized/resistive and turned into heat producers.

The clips must be free to self align with the fuse end cap in order to make full contact.
They must make firm contact, such that you cannot remove with just fingers.
The contact area must be bright and shinny with even clear oxidation removed.

Usually, once the plastic has melted, the only option is to replace it.

The main fuse normally carries up to 16 amps before the current makes enough heat within the fuse to melt the link.  If the fuse is heated externally, it will melt at a lower current rating.  (You can melt the fuse link with a soldering gun and NO current flowing through it.)

The standard running current on a stock bike is about 10 amps.  Naturally, adding more loads to the circuit brings it closer to the "blowing" point.

How many watts/amps did you add?

[bollingball]

The good thing about HondaMans fuse block is it will come with the correct connector for your bike so you won't have to solder anything if you don't like to mess with stuff like that.
It sounds like this would be a good time to go over all the connections on your bike. Do it now or on the side of the road up to you. Here is a good place for anything you might need.

http://www.vintageconnections.com/
And one more
http://www.oregonmotorcycleparts.com/

Ken

[KC3]

If the fuse box has melted, solder melted, it is not due to over current, but rather the fuse clips have become oxidized/resistive and turned into heat producers.

The clips must be free to self align with the fuse end cap in order to make full contact.
They must make firm contact, such that you cannot remove with just fingers.
The contact area must be bright and shinny with even clear oxidation removed.

Usually, once the plastic has melted, the only option is to replace it.

The main fuse normally carries up to 16 amps before the current makes enough heat within the fuse to melt the link.  If the fuse is heated externally, it will melt at a lower current rating.  (You can melt the fuse link with a soldering gun and NO current flowing through it.)

The standard running current on a stock bike is about 10 amps.  Naturally, adding more loads to the circuit brings it closer to the "blowing" point.

How many watts/amps did you add?

Thanks for the info TwoTired. I replaced my stock tail light with an LED light (approx 15 LEDs which I presume draws very little current) and two dual filament 21W bulbs (1.75X2=3.5A) so I would say I added at most 5A. I have ordered a new fuse block and will post back with pics & wire short 'hunting' results asap.

Look for a short somewhere or a bad ground or corroded terminals to fuse. Swap in with a newer bladed fuse would be highly recommended.

By the by, Indiana requires turn signals for all bikes manufactured 1/1/56. I would assume that means front and rear.

True, but it also states that you can have 'mechanical' turn signals..i.e. throw up your hand signals when a cop is around & at 4way stops (at least that's how I interpereted 'mechanical' turn signals ).

Thanks for all the help everyone!
Cheers-
KC

[OldSchool_IsCool]

It sure quacks like dirty/weak fuse clips.  The blade box kit will correct that.  And if your stock box is melted beyond repair, you may have no choice but to replace it anyway.

But, if you do want to chase your harness for a short anyway, replace your fuse with a 12v light bulb.  The bulb will burn brightly when a short is active.  It will dim or go out entirely when the short is gone.  It's a LOT less expensive than uesing a fuse as your test device.

[TwoTired]

Thanks for the info TwoTired. I replaced my stock tail light with an LED light (approx 15 LEDs which I presume draws very little current) and two dual filament 21W bulbs (1.75X2=3.5A) so I would say I added at most 5A. I have ordered a new fuse block and will post back with pics & wire short 'hunting' results asap.

If the stock bike averages 10 amps and you added 5 amps to it, the draw will be 15 amps, which is the stock fuse rating size.  Step on the brake and the current will go over rating and dutifully protect.  That's even if the fuse contacts are perfect.

[KC3]

  ;DThanks for all the advice everyone!! Got 'er back on the road today! Check out the pics for my $15 fix (sorry Hondaman) I'm broke and I do like soldering and that kind of stuff 

Hooked up an ammeter and chased down a short in the headlight bucket too. I guess I should have been more careful when I tucked 'em all in there the first time.  Well now its fixed and running like a champ.

Cheers!
KC