This cb125 is going to be the death of me

pidjones said:
This! Going to 12 volt system is not going to fix a parasitic ground problem. The bike is simple enough that it shouldn't take over 10-15 minutes to find the problem.
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I that's what i thought too. Admittedly I'm not that great with a multimeter. Im used to working on MX bikes with basically no electrical systems . I do understand that changing to 12v will not solve the problem.

Is it possibly that I could be the battery since I assumed it was good because it took a charge?
 
Absolutely possible its the battery. But its more likely that you have a parasitic draw and you need to eliminate that drain or rule out the possibility before putting a new battery.

I have had multiple cheap lead acid batteries that have been bad right out of the box.
 
So I went to 2 auto stores and the looked at me weird and said they "couldn't test 6v" so I went batteries + bulbs and they tested it and as soon as they put any load on the battery it just took a dump and dropped to 1v .....so there is that
 
Its charging now and well see if thats the entire issue. I have a strang suspicion there is more to it
I'll check back when I get it put back together
 
So it starts right up.......but the problem persists. I do think I found something though. When I tested the back of the plug that connects the harness to the rectifier with the key off I was getting battery voltage at the red/white (6.4vdc) and .7vdc at the green, yellow and pink. But when I unplugged it and tested the same wires on the harness side there was only the batt voltage at the r/w and 0 at all the other 3.

Then I tested the rectifier on it's own w the diode function and I got 3 readings in one direction (none of which beeped) but they were .546, .530, and 1.262 the last one raises a red flag because everything I have read about testing them says that the numbers should be the same

I feel like I'm getting somewhere (I could very well just be a complete idiot)

Please bear with me I'm trying here.

Still dosent explain the signals not flashing though
 
If its got the original selenium rectifier and regulator I would replace.

https://www.ebay.com/itm/6V-Voltage-Regulator-Rectifier-For-Honda-SL100-SL125-CB125-S-CB125S-CL125-SB100/292474372996?hash=item4418d4c384:g:KT0AAOSwUN9an5NH

Same goes w the signal flasher.
 
Alright so I ordered both. And could anyone tell me what i should see for AC voltage out of the stator wires ? I'm getting 1 (cant remember if it was the yellow or white) at about 40 ish at 3k rpm and the other 2 are 5vac
 
SOS! I dont get it. I got the draw to go away, re adjusted valves and re checked points gap and timing cleaned carb again for no reason. New battery. New rectifier. New blinker relay (they work now). I DO NOT GET IT . I literally feel like an idiot that this little simple bike is stumping me.

When I take the boot off the carb I can see fuel blowing backwards out of the back side of the carb and I have tired all the needle positions and 90, 98, and 100 main jets and all settings with air screw WHAT AM I MISSING!?

It might be time to tear into the top end.
 
So its running now and the electrical all checks out good.

Is it just running poorly? What are they symptoms?

Or is it still riding great for a mile then sputters and dies.

I don't think think there's a problem w the top end. So long as your setting valves properly, points opening on marks, etc.

After getting it running w static time. Did you dial it in properly w a strobe timing light?
 
trek97 said:
So its running now and the electrical all checks out good.

Is it just running poorly? What are they symptoms?

Or is it still riding great for a mile then sputters and dies.

I don't think think there's a problem w the top end. So long as your setting valves properly, points opening on marks, etc.

After getting it running w static time. Did you dial it in properly w a strobe timing light?
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At least I thought the electrical checked out until I tested the main fuse and I have 0 power at the fuse.

It does not take more than like 1/3 throttle. It is spitting fuel backwards out of the carb I clean the carb again last night and triple checked valve clearance. Getting discouraged it will idle ALL DAY but the riding good for a mile had stopped and nothing I do has any effect at all on it.

I did not do the strobe but it would not run the horrendously. There is something else going on.

And I agree that I don't think it's the top end either. I'm just running out of ideas.
 
swizbee42 said:
It is spitting fuel backwards out of the carb I clean the carb again last night and triple checked valve clearance. Getting discouraged it will idle ALL DAY
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Sounds to me like a valve timing/clearance issue, or you have a vacuum leak. Have you set the cam chain tension?
 
advCo said:
Sounds to me like a valve timing/clearance issue, or you have a vacuum leak. Have you set the cam chain tension?
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Yes I have done that too. Unless it magically jumped time. I guess I'll have to pull the points and stuff and check the cam timing too
 
swizbee42 said:
At least I thought the electrical checked out until I tested the main fuse and I have 0 power at the fuse.

It does not take more than like 1/3 throttle. .
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0 volts to ground from hot side w fuse pulled out, key on?

Did you pull, clean, grease and check function of the advancer?
 
trek97 said:
0 volts to ground from hot side w fuse pulled out, key on?

Did you pull, clean, grease and check function of the advancer?
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Fuse pulled (brand new honda fuse), key on, hot side 0.00 volts......but funny story I just checked it and now I have voltage there.

And yes the advancer seems to be fine. I'm not quite sure how it actually works but it seems to be moving freely
 
I'm sorry. You guys must think I'm mentally challenged, I swear I'm trying. I'm going to pull the points and advancer and check the cam timing
 
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