'81 CG 125 no ignition light

[DrSnoosnoo]

Hello dons of BCF

I have a problem which some of you may be able to give me pointers to look at tonight.

I rode home on the CG last night and it was working brilliantly - even got her up to 60 mph!!! parked her up in the garage and left.

This morning I go out, put the key in the ignition turn, usually this turns a light on, in the clock to show neutral and that I can start her up.

This time however I got no light and the bike rolled forwards and backwards in and out of the garage so it was in neutral but I obviously couldn't get her to start.

The battery has a solid 6.42 V in her and I (very quickly) had a look at the main fuse attached to the wires by the battery and the fuse looked OK but even after taking it out and just connecting the connectors, still nothing.

Any ideas?

Thanks in advance!
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I'm Sam; Northern, Ginger, Lover
Did have: '95 ZZR600 '83 CG125 '97 ZZR1100 '15 Hypermotard 821 SP Do Have: '10 ZX10R

[WD Forte]

Just had look at the pdf I have of early CG125 6V models and there's no connection between the neutral switch and circuit and the ignition system to suggest any safety interlock you find on many bikes.
(Wont go if not in neutral, side stand down, clutch in etc)

What I see is a simple
Power to bulb at ignition on
Ground from bulb held high until neutral selected
In neutral, the switch closes to ground and bulb lights
Thassit!

I'm guessing the lack of neutral light and non starting are both linked to a connection problem
If everything else worked but you had no N light, I'd just check the switch functions
soooo....

In no particular order:
Check connections.
Check the engine has good grounding to battery negative
Check main switch connections and function.
No power getting in/out here will mean no power to neutral light and ignition ( plus the other stuff)
Check for a spark
____________________
bikers smell of wee

[DrSnoosnoo]

Thanks for that, it's half what I expect but the pdf I have of the circuit diagram is missing chunks from it so I lose where lines go. I was just gonna get the mulitmeter out again and check my connections. There's nothing to go wrong on these things I keep telling myself. The engine runs, just need to make sure it's connected to some electricity!

Cheers
____________________
I'm Sam; Northern, Ginger, Lover
Did have: '95 ZZR600 '83 CG125 '97 ZZR1100 '15 Hypermotard 821 SP Do Have: '10 ZX10R

[WD Forte]

his time however I got no light and the bike rolled forwards and backwards in and out of the garage so it was in neutral but I obviously couldn't get her to start.

A wee bit confused here
I read this as 'no N light and wont start'
If it will start and all else is fine, its just the switch or connections
____________________
bikers smell of wee

[mudcow007]

you checked the bulb?

my neutral light didnt work when mine was in neutral but would flash when hitting lightspeed (in 4th doing 50ish)

CG's dont have sidestand switches i dont think?

[blurredman]

Maybe getting the beast up to 60mph shook appart some earth points?
____________________
CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S, 1979 MZ TS150.
Current: 1973 MZ ES250/2 - 18k, 1979 Suzuki TS185ER - 10k, 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (295cc) - 40k, 1989 MZ ETZ251 - 51k.

[Chalky.]

It isn't in a false neutral at all is it?

[DrSnoosnoo]

[blurredman]

It's too much of a coincidence that the light no longer comes on, when you cannot start it. I had a CG myself so I understand what you're saying. But try all the simple things first.
____________________
CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S, 1979 MZ TS150.
Current: 1973 MZ ES250/2 - 18k, 1979 Suzuki TS185ER - 10k, 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (295cc) - 40k, 1989 MZ ETZ251 - 51k.

[DrSnoosnoo]

Now then, guess who feels a pillock? The bike is fine. Last night was messing with adjusting the gear lever. And must have put it out of neutral or not quite in or whatever. I got home this eve and had a fiddle aroubd and got her to start. Difficulty starting must have been just a difference in temp.

Ill see what its like in the morning!
____________________
I'm Sam; Northern, Ginger, Lover
Did have: '95 ZZR600 '83 CG125 '97 ZZR1100 '15 Hypermotard 821 SP Do Have: '10 ZX10R

[unitynotsocri...]

bulb .....POWER COILS.......IGNITION WIRING...


you have one of the most classic nickalble bikes remember .the key switch ..when turned off shorts out the points ....

so a faulty (usually corroded backpins/sprimgs in the barrel base/) barrel can cause problems . Theres two coils on the crank , one for charging and one for lighting . When you switch the lights on they show glow a little when being kicked over, even if the engine does'nt start , this will show the lighting coil is ok .

the charging coil charges the battery through a cheapoish rectifier so this may be faulty .

I've found that crazy voltage readings indicate knacked rectifier/regulator and ballast resistor problems , but a blown rectifier will flatten the battery much quicker .

you can check the power coil readings


AND REMEMBER

being a points model a small insulating plastic/fibre washer on the points assembly can sometimes be assembled wrong and short the points out....
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nearly a normal tax paying tosser.......with ferrileness suzi100,cg125,cb125scb100n,cb175,cd100,cj250t,kh250,c15,125 bantam,super 6,rickman gs750,xt500,250rs,dt175,lifan125,dolomite1850,metro,Morris220ld,morrisfg,leyland princess,range rover,corsa,vw camper .now struggling with legs. MORE ORDER = MORE CHAOS