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Discussion Starter · #1 ·
The other week I was riding and my bike acted like it was running out of gas. I had just filled up so that wasn't it. So the bike died in my driveway and wouldn't start again. When I was trying to test for spark I saw some smoke and the ground wire for the rectifier burned up. I have since replaced it and was putting everything back together after checking the negative strap (which was fine) and chasing all of the wires to look for frays or possible grounding situations. I checked for spark and was still getting none. After checking and testing the coils etc I pulled off the caps on the end of the spark plug wires and got spark. Then I reinstalled them and now the plug was firing. After putting the plugs back in I tried to start it and it wouldn't. After checking for spark they weren't. I pulled the ends off and was getting no spark either. I am also in the process of redoing a 1965 S65 Honda and it's doing the same thing. It gets spark when I pull out the spark plug sometimes but not always especially when they are in the head. Any ideas? Could it be the condesors?
 

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Sensei
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It is more likely bad coils, bad plug boots (caps) or a weak battery...... You should get spark even with no condensers in circuit.... Could just be bad plugs.....
Essentially, the condenser fires "backwards" through the points preventing metal transfer from one contact to the other.... Otherwise, they would build up a small "weld" that would damage the points,and alter the timing.....
 

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Discussion Starter · #3 ·
So the battery has been fully charged and the plug boots pulled off and getting no spark. If it was the coil wouldn't one go bad not both. Also if I ordered new coils would I get the 3.0 ohm or the 5.0 ohm? I ordered new points last week so hopefully that will fix it since these are 39 years old. :)
 

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Sensei
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Could also be an intermittant connection in the "kill" switch, dirty power connections anywhere in that circuit, or a bad ground...... You can test the coils by firing them directly off a good battery Hook blue (or yellow) to B-, and hold HT lead near but not quite touching B-..... Touch Black/white wire to B+ and then break that connection.... HT lead should spark to B-
 

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Discussion Starter · #5 ·
Thanks for the info. I'm not sure what you mean by blue- could you elaborate? I had already thought of the kill switch. I was going to try and clean up the connections. The thing about ms is I'm a wiz at mechanical but I'm completely illiterate about electrical. The thing that makes me think it's a wiring issue is that my 65 is doing the exact same thing. Thanks for your help.
 

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Sensei
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B+ is the battery positive terminal...
B- is the Battery negative (ground side)
Blue and/or Yellow are the "color" of the coil wires that ultimately go to the points .....
By hooking the coil's "point wire" directly to B-, you simulate the points being closed and the coil gets power.... Breaking either coil wire's connection causes it to "fire"....(hence the touch and break at B+ with the black/White wire....while this is "backwards", it achieves the same circumstance, and allows you to hold the HT (spark-plug) wire near the B- terminal more easily.....
You could "hook-up" the Black/white to the B+ and touch and break (remove)the "color" wire on B- while you observe the HT lead held close to B- (for the spark jump).... Either way works to test the coil, it is just whichever way is easier for you....
 

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Discussion Starter · #7 ·
So I think I figured it all out. I haven't been able to get a bulb for the high beam indicator so it was just loose in the headlight housing. When I was chasing the wires for the kill switch I noticed on the wiring diagram that the kill switch black wire ties directly to the headlight. When I opened up the headlight assembly the wire had pushed up through the indicator housing and I'm sure that it was grounding out on the headlight which in turn was killing the spark. I also imagine that it had something to do with the rectifier burning up the ground wire. Yeah baby. I get to enjoy more riding before winter. Thanks again for all of the help and once I get her back together again I'll post some pics.
 

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Sensei
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The Black wire is the main power "buss" throughout the bike once the ignition switch is "on"..... It has NO direct connection to the rectifier, although it does act as the "trigger" to the regulator when (and only when) the voltage in that wire is in excess of 13.7 Volts..(high revs)...
The rectifier Green would ONLY "fry" IF there was no other way for a source of high amp draw to ground and complete the circuit back to the battery negative.... Usually, this would be the starter motor IF it was a single item... The whole bikes electrical system grounding through that skinny wire would/could also "cook" it..... That's why I suggested you check your battery to frame/engine ground first....It could be a dirty connection at the battery terminal itself, not necessarily the one at the motor mount bolt....
 

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Discussion Starter · #9 ·
So there was a dirty connection at the ground wire (not to the frame) so I repaired it. I also replaced the points and condensor as well as installed the carb rebuild kit. I went for a spin and it was running super. Allthough when I really opened it up it felt like the bike was running out of gas. It kinda sputtered and spat put I was able to rev it up and make it home. I figured it was the carbs but later on I found out that it was actually the left side coil was giving out. Eventually it just completly crapped out. I swapped the coild and found that it was indeed the left side coild and nothing else. Dyna's on the way and should be riding next week. I can't wait. :D
 

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Discussion Starter · #10 ·
Heres a pic of her
 
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