74' CB125 Electric issues. Need help

swizbee42

New Member
Ok so I will preface this with, I am no wizard with a multimeter but I do somewhat understand what I should be looking for. And I have search this forums and many others with no luck.
So I got this 74 cb125 for free and it was sitting for 30 years. I have cleaned the gas tank and carb about 10 times. Gapped the points and done static timing. The battery is fairly new. I have spark and I'm getting fuel.

It will start when the battery is full charge (seeing 6.3v w key off) and when it is running I can see 7.03v so I know its charging. It will idle and run perfectly (idled for about 20 mins with no voltage drop across the terminals)

But here is the issue. It WILL NOT go above 7k rpm and when you hit the brake, turn on headlight or blinkers (which dont flash, they stay solid) it wont go above 4k rpm.

And I checked the battery was 6.3v when I turned it off, 4 hrs later with the key off the whole time it tested 3.03v

So i guess my question is, what is my next test? I've been beating my head off the wall.
 
You've got a short somewhere. Grab a wiring diagram and set your multimeter to ohm setting for continuity and start going through one circuit at a time until it beeps. Being that you're having the trouble when you use lights, that's probably a good place to start.
 
Ok I will have to do that. I did check a few things. But could someone explain to me why the bike would bog at 7k if I have a short? Is the short taking power from the coil and it cant burn the available fuel?
 
Yeah, essentially it's robbing spark. Oftentimes, it will feel like you're running out of fuel, which really can confuse things, but really the coils aren't firing.
 
That is EXACTLY what it sounds and feels like. It feels like a main jet issue but I know it's not because of the lights blinkers
 
Also check the coil is the correct one.....prob not the issue but it may save some head scratching ;)
 
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