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Discussion Starter #1
I just bought this 78 CM185T this week. I drove it around before buying it and everything was great. I didn't have any issues driving it around that day. But at night I realized the headlight didn't turn on when I started the bike. I had to switch on the Hi-beam for the light to come on. Then I noticed the blinkers didn't blink, but were just solid. I tried the horn and found that it didn't work.

IMG_3184.jpg

I have done some checks with a multimeter to try and diagnose the issue.

Stator: I checked the connector and had continuity between the Pink, White and Yellow wires.
Rectifier: This one was pretty weird. The FSM has a diagram of which wires to test and the polarity. Testing the Red and Pink wires didn't give me the continuity beep but the multimeter read 543 Ohms. I got 547 Ohms when I tested Red and Yellow, again no beep. The third set, Red and Green was Open Line. The Pink and Green had no beep and 547 Ohms. And the Yellow and Green was Open Line.
View attachment 290502

If I am interpreting these results right, then my rectifier is definitely bad right?

I decided to pull off the headlight and test the other connectors. I followed the FSM charts for these too.

Ignition Switch: With the key in the off position, I shouldn't get continuity between any of the leads. But I got continuity between Black and Brown/White. I also got continuity with Red if the negative probe was on it and the other on Black or Brown/White. With the key in the middle ON position, all the leads should have had continuity. But Brown had no continuity.
View attachment 290504
So my ignition switch is also bad?

Turn Signal: According to the FSM chart, only certain wires should have had continuity depending on where the turn signal switch was located. Regardless of the switch, I got continuity between them all.
The turn signal is busted too?

Engine Stop Switch: With the switch in OFF position, there should have been no continuity but there was.


So in conclusion, is nearly everything electrical on this bike messed up? Are all these issues caused by one fault? I'm pretty new to this business so did I do these tests wrong?

Hopefully someone else has had issues like this before.
 

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Sensei
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You are performing irrelevant tests, as the rectifier has polarity that must be considered, and ALL the lighting is ultimately connected by a common ground....
You are close enough to phone me and I'll be happy to guide you through the correct tests....540-525-5199......

Make sure your battery is fully charged, you have a multimeter, and basic hand tools handy.....
 

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Discussion Starter #3
Thanks for the help 66Sprint. I spent a while cleaning the electrical contacts in the headlight area and under the seat last night. The headlight is working much better now and now the horn works! The blinkers still don't blink unless I am at a high rpm but at least there is some progress.

I noticed some funny wiring under the seat though. There is an orange wire that is connecting the black wire on the blinker relay to a brown wire that I believe connects to the tail light. In the picture you can see that someone taped the orange wire to the black one. You can also see the brown wire that was connected to it and at the very bottom the other end of the brown wire that should have been connected. The orange wire is a female spade connector and the brown one is a male bullet connector, so they are clearly not meant to connect. If my description is confusing, take a look at the wiring diagram that I colored.

Anyone know why the previous owner did this?

IMG_3205.jpg
WeirdWires.jpg
 

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Sensei
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That was likely done so the taillight would come on because according to your tests, the ignition switch does not make the brown/white to brown connection....
Phone again, and I'll explain further, but you will have to post the results for the group....
 

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Discussion Starter #5
Update: After talking with 66Sprint, I tested the alternator and the battery with a multimeter. I unplugged the alternator and jumped the blue wire back to the wiring harness then measured the AC voltage across the pink and yellow wires and the pink and white wires. Across one I measured about 6 volts at idle and revved it up above 50V. The other was about the same but above 40V.

Then I tested the DC voltage at the battery as I revved the bike. It never read higher than 6V no matter how high I revved the bike.

So I'm thinking I need a new rectifier. Any ideas of where I should get one?
Or did I do this all wrong? Because that is definitely possible.
 

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Sensei
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You did the test correctly, and your alternator appears to be fine......
(although I would be interested in knowing the approximate revs or throttle positions where the AC output was 18 VAC and 25 VAC)

It DOES appear that you need a new rectifier/regulator unit........
 

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^^^and what Steve means specifically is to replace the rectifier (and separate regulator if the bike has one) with a modern rectifier/regulator combo unit. One of our sponsors happens to sell the best combo unit for as good a price as you'll find as compared to all the other units available out there, and backs it up with plenty of support here from the owner himself (HT member Sonreir).
 

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Sensei
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Tom,
Member will have to contact Matt directly, as this is a 6 Volt system.....
 

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For everyone else following this thread, I have a 6V R/R we've been working on and I have the second sample (first one didn't work as intended) from the manufacturer on Friday.
Riley will be assisting with the testing on his bike.
Excellent!
 

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Discussion Starter #13
Alright, quick update. While waiting for the regulator from Matt I decided to order one from ebay. I screwed it on and plugged it in and measured the voltage across the battery at idle and as I revved the bike. It measured about 6V the whole time. So I'm beginning to think there is something else that is wrong.

I decided to drive it home anyway (I had been keeping it at work). It died a few times at stoplights (luckily it wasn't very busy) but I was able to kick it back to life and nearly get home. It died again on my street and while trying to start it again I noticed a burning smell. I couldn't get the bike started and walked it back home. I found that the new regulator crapped out! Take a look at the pics and let me know what y'all think. Faulty regulator? or is something else wrong that caused this thing to melt?

IMG_3277.jpg
IMG_3276.jpg
 

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Sensei
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Do me a favor, and take a picture of your battery showing the cable connections.........
 

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Sensei
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Several things......
Battery connections SEEM to be dirty/poor/weak......
Can't tell from pics but can't see electrolyte level between upper and lower lines......Is battery properly filled with DISTILLED water?
Unit on bike is a RECTIFIER only, Not a combined unit, so no REGULATOR (and it IS burnt on at least one of the internal diodes, so is BAD.....)
Perhaps it's time for another phone call.........
 
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