Need some electrical advice before I fry something

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Need some electrical advice before I fry something

trapper
Hey all,
So here's my issue.. Minor but figured I would hit this up before I do something stupid and fry the bike.
'81 CB750c, Just removed the big display cluster (tac, dummy lights) and noticed that in doing so, my left rear blinker now doesn't light up. Bulb is still good but, it's getting no power. Kinda expected something like this so, it wasn't a shock. I'm wondering If I were to take the wires that ran into the back of the tac and light cluster, and splice them together. Effectively completing the circuit and bypassing those displays, could this fix my issue? Or would it fry something? Kinda a silly question, I know. But when it comes to electrical, like many home mechanics, I'm clueless. Figured going to a bunch of other do it yourselfers would help before I go trying silly stuff.
Thanks in advance guys and gals.  
It ain't a custom till you have customized it yourself.

1981 CB750c (current daily ride and build)
1980 GL500 (Stripped and rebuilding)
1981 CM450 (Stripped and rebuilding)
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Re: Need some electrical advice before I fry something

shinyribs
Administrator
I'd say you're on the right track. The indicator for the turn signals is basically just a turn signal itself. That's probably where you lost your circuit.
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Re: Need some electrical advice before I fry something

shultz_1978
In reply to this post by trapper
I my self would hock a test light up to the indicator light wires and see if the turn signal works.

Its a start
Simple if some one else can, why can't I
Jamie
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Re: Need some electrical advice before I fry something

sgtslag
In reply to this post by trapper
The bulbs in the instrument cluster form a load on the lighting circuit.  Shorting the wires, even if you get the correct wires crossed, will change the load on the flasher circuits.  A better option is to find a friend who knows electric circuits to help you troubleshoot it.  If you cross the wrong wires, you could short something out, likely blowing a fuse, and possibly causing other problems.  Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
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Re: Need some electrical advice before I fry something

trapper
This is why I asked
Good to know. I never thought about the bulb/load situation but, makes sense. Unfortunately I lack a friend with that knowledge around here.
What about putting inline fuses in place of the bulbs? I'm just spit firing here of course. As I said, most electrical is greek to me.
It ain't a custom till you have customized it yourself.

1981 CB750c (current daily ride and build)
1980 GL500 (Stripped and rebuilding)
1981 CM450 (Stripped and rebuilding)
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Re: Need some electrical advice before I fry something

sgtslag
A fuse does not burn any watts, so it does not load the circuit; it acts as a dead short, until the current exceeds its rating, then it burns open.

For an understanding of electricity, in general, and as it pertains to motorcycles, in particular, here is a fantastic book:  Amazon link.

I went to school to be an electronic technician, did component level troubleshooting/repair for 3.5 years.  I have been a computer technician for 23 years.  [Don't tell anyone, but even I learned a few things from reading this book!...  ]  This book is fantastic in its explanation of electricity, and simple circuits.  Check your local library for it, and see if they can borrow it from a regional library if they don't have it themselves.  The author explains voltage, current, resistance loading, induction for alternators/generators, and other things, quite well, in easy-to-understand language, with examples which are easy to comprehend as well.  This is not a quick solution, but it will pay dividends for years to come.  It's a worthy investment of your time and energy.  Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
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Re: Need some electrical advice before I fry something

seestheday
Thanks for the tip sarge.  I just ordered that book.

I recently fought through an indicator issue recently myself.  Ended up blowing two fuses in the fuse box and my main fuse.

I had to get the main fuse from a motorcycle shop and drive around to find an electrical supply shop that carried the fusebox fuses I needed.  Remember to bring your blown fuses with you.
1981 CB750K with 900 cams
90K KM's, rebuilt head, rebuilt carbs, upgraded valve stem seals

My wife's recipe website that I'm trying to help promote: Strawberries for supper. Yes, I am a lucky man.

My cb750 video site
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Re: Need some electrical advice before I fry something

trapper
Thanks Sarg. That's real helpful. I will look in to that book. Sounds like a great thing to have in the garage. Until then, I think I have decided to customize the display a little. Put it back but in a way that will still work with my rat attempt. Giving it the bulbs yet still cleaning up that whole cluster.
It ain't a custom till you have customized it yourself.

1981 CB750c (current daily ride and build)
1980 GL500 (Stripped and rebuilding)
1981 CM450 (Stripped and rebuilding)
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Re: Need some electrical advice before I fry something

sgtslag
In reply to this post by seestheday
Sees, if you are referring to the 30 Amp main fusible link, it can be replaced with a modern, mini blade fuse, quite easily.  I picked up a fuse holder at Wal-Mart for less than $10; crimped on connectors to the ends of the wires on it (soldering would be much better, but I never had a problem with it...), then I screwed those in place of the fusible link, under the side cover.  I added a couple of extra 30-Amp fuses to the bike's fairing pockets, just to be safe.

Here is the same unit, from Radio Shack, for less than $5:  30-Amp Mini Blade Fuse Holder.  This one even comes with an LED to indicate that the fuse is blown!  The fusible links work just fine, but they are less commonly available, so harder to find replacements.  The modern mini blade type fuses are available all over, in many sizes, up to 30 Amps (may be available in larger amperages, don't know); they're easy, and quick to change, too.  Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
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Re: Need some electrical advice before I fry something

trapper
Problem solved. Just did a little bit of fabricating/welding with the old mount for the cluster. Cut up 2 light displays and wired the indicators back in. Still has the look I want yet fixes the issue.  
It ain't a custom till you have customized it yourself.

1981 CB750c (current daily ride and build)
1980 GL500 (Stripped and rebuilding)
1981 CM450 (Stripped and rebuilding)
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Re: Need some electrical advice before I fry something

sgtslag
Nice, clean, simple look.  Cheers!
1979 CB750K (sold, 2012, but not forgotten)
1983 Kawasaki 440 LTD Belt Drive (sold, 2011)
1993 Kawasaki Voyager XII
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Re: Need some electrical advice before I fry something

shultz_1978
In reply to this post by trapper
Simple if some one else can, why can't I
Jamie