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Author Topic: Bad Ignition??  (Read 1512 times)

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Offline mikejorg

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Bad Ignition??
« on: November 30, 2013, 02:23:54 PM »
Went to go for a ride the other today and turn the key and nothing happens ... Charged and checked the battery and still nothing. No lights at all. Checked my main fuse and it was good as well. Has my ignition gone bad? What else should I look for?
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Offline MoMo

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Re: Bad Ignition??
« Reply #1 on: November 30, 2013, 02:56:31 PM »
Try wiggling the wires behind the switch and see if that helps, also check battery contacts for corrosion...Larry
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Offline mikejorg

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Re: Bad Ignition??
« Reply #2 on: November 30, 2013, 03:09:08 PM »
Battery contacts are good, made sure of that. I'll try and wiggle the wires to see if that does anything.
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Offline mikejorg

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Re: Bad Ignition??
« Reply #3 on: November 30, 2013, 03:55:33 PM »
Just went and wiggled the wires and cleaned off the battery contacts again. Still nothing. Any other ideas?
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Offline MoMo

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Re: Bad Ignition??
« Reply #4 on: November 30, 2013, 05:15:36 PM »
Did you check where the negative cable attaches to the frame?  BTW,  what model and year is the bike?...Larry
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Offline mikejorg

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Re: Bad Ignition??
« Reply #5 on: November 30, 2013, 05:36:36 PM »
It's a 77 CB750K ... Would this be on the right side of the bike? Think I know where you're talking about but just want to be sure. Currently don't have my manual with me.
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Offline scottly

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Re: Bad Ignition??
« Reply #6 on: November 30, 2013, 05:45:28 PM »
How did you check the fuse? They can look good but still be bad. Also, the fuse-holder contacts can become corroded and /or overheated. Do you have a voltmeter?
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Offline mikejorg

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Re: Bad Ignition??
« Reply #7 on: November 30, 2013, 05:56:08 PM »
I checked for corrosion on the fuse holders and everything looked good there, but can't check to see if it gets overheated (let me know if I'm wrong on this), I literally have no power. The nuetral/oil lights don't even come on when I turn the key. I do have a voltmeter/multimeter.
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Offline scottly

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Re: Bad Ignition??
« Reply #8 on: November 30, 2013, 06:14:20 PM »
Put the black lead of the meter on the negative battery post, and the red lead on either side of the main fuse; you should read 12V at both ends of the fuse. Do this test with the ignition switch off first. If you do have 12V on both ends of the fuse, turn the ignition switch on and test for voltage again.
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Offline mikejorg

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Re: Bad Ignition??
« Reply #9 on: December 01, 2013, 12:13:02 PM »
Tested both with the ignition off and on and I got 12.71 every time. Double checked all the battery contacts and everything is extremely clean. What's next?
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Offline MoMo

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Re: Bad Ignition??
« Reply #10 on: December 01, 2013, 12:23:59 PM »
Find the red wire going into the ignition switch plug and make sure you have 12v there.  The red wire is the feed and the black wires are 12v out when the switch is on...Larry
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Offline mikejorg

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Re: Bad Ignition??
« Reply #11 on: December 01, 2013, 12:47:04 PM »
I get 12v from the red, but getting nothing from the black when the switch is on.
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Offline MoMo

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Re: Bad Ignition??
« Reply #12 on: December 01, 2013, 12:50:27 PM »
That should indicate a bad switch.  Is it an aftermarket Emgo?
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Offline mikejorg

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Re: Bad Ignition??
« Reply #13 on: December 01, 2013, 12:57:24 PM »
Don't believe so. It could be the original. The bike had 12800 miles on it when I got it and its got 15300 now.
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Offline mikejorg

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Re: Bad Ignition??
« Reply #14 on: December 01, 2013, 01:10:08 PM »
Just checked it's definitely OE style square plug
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Offline MoMo

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Re: Bad Ignition??
« Reply #15 on: December 01, 2013, 02:24:57 PM »
Quote from: mikejorg on December 01, 2013, 01:10:08 PM
Just checked it's definitely OE style square plug


Still,  with 12v in and nothing out indication is the switch is bad.  You could jumper red to black...Larry
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fendersrule

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Re: Bad Ignition??
« Reply #16 on: December 01, 2013, 02:28:10 PM »
MoMo is on this like a hawk, but I wanted to add one thing to check (if it makes sense based on what you've done so far):

REMOVE the switch (easy to do) behind the key lock. You will see some brass prongs. Make sure this whole mechanism is cleaned and reinstall.
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Offline MoMo

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Re: Bad Ignition??
« Reply #17 on: December 01, 2013, 02:51:10 PM »
Quote from: fendersrule on December 01, 2013, 02:28:10 PM
MoMo is on this like a hawk, but I wanted to add one thing to check (if it makes sense based on what you've done so far):

REMOVE the switch (easy to do) behind the key lock. You will see some brass prongs. Make sure this whole mechanism is cleaned and reinstall.




Yep,,, I've seen corrosion on those prongs preventing the bike from starting.  Good thought Fenders..
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Offline mikejorg

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Re: Bad Ignition??
« Reply #18 on: December 01, 2013, 02:56:05 PM »
Thanks for all info on this MoMo, scottly, and fendersrule. I'll check the prongs and clean them out. If that doesn't work do you recommend going with an aftermarket Emgo or sticking with OE style?
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fendersrule

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Re: Bad Ignition??
« Reply #19 on: December 01, 2013, 03:29:35 PM »
Stick with OE IMO. I ordered a new aftermarket switch from CB750Supply.com. They claimed it was for the 77-78, but it wasn't even close on the fitting.

So I just cleaned mine up and reinstalled. Worked for a year so far with no issues....

With the switch goes bad, it will exhibit the same behavior....you turn the key to "run" position and NOTHING happens. No lights, so switches, nothing.

Mine was so bad that the bike would turn itself off while driving...I had to "jiggle" the key to keep it working or to start it. A cleaning with contact cleaner, as well as steel wool (or any gentle abrasive) to the prongs. Also, look at the other side of the switch (that mounts to the actual key mechanism. Looks for corrosion and make sure it's all cleaned. It will all make sense when you remove it. They don't go "bad" from what I can tell...it's just a simple connection mechanism that needs to stay cleaned.
« Last Edit: December 01, 2013, 03:34:57 PM by fendersrule »
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Offline MoMo

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Re: Bad Ignition??
« Reply #20 on: December 01, 2013, 03:56:21 PM »
You can disassemble and clean the contacts of the switch if cleaning the prongs does not work. If you do be careful as several parts will fall out-but that never happened to me, yea right
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Offline mikejorg

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Re: Bad Ignition??
« Reply #21 on: December 01, 2013, 06:12:30 PM »
Prongs didn't look that bad but I went ahead and cleaned them anyway. Plugged it back in and bam everything turns back on! Thanks everyone for the help!
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Offline scottly

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Re: Bad Ignition??
« Reply #22 on: December 01, 2013, 06:39:19 PM »
 8) 8) 8)
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Offline mikejorg

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Re: Bad Ignition??
« Reply #23 on: December 01, 2013, 08:30:00 PM »
Just got back from a ride, everything is good. Thanks again everyone!
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Offline MoMo

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Re: Bad Ignition??
« Reply #24 on: December 02, 2013, 01:38:09 AM »
Good for you, glad you're back on the road...larry
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