Bloody electrics!
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Hooked
1997 T5 Classic
Joined: 26 Dec 2008
Posts: 186
Location: Durham UK
Fri Feb 20, 2009 7:19 am quote
How do, ive got a 1979 px125. It was 6volt electrics and was shot so ive started to convert to 12v cdi but im confused.

Ive attached the new stator and cdi unit.

the stator has green/blue/black/red/white wires
the cdi unit has connectors red/white/green/green and a separate yellow coloured wire coming off. as well as spark lead

Now in theory i thought, connect up the cdi, eg. red/white and green wires.

Connect a spark plug, earth to engine casing and in theory if i hit the kitstart it should spark.Am i correct or have i missed something?

The wiring diagrams about dont help much and i cant find a conversion guide anywhere.

Not bothered about lights etc yet just wana get plug sparking!
Driving me mad

Ive checked resistance on the stator as well as seen in a post, its fine
Moderator
1962 GS160mk1, 1963 GS160mk2, 1965 SS180, 1974 Rally 200, wife's LI150
Joined: 05 Mar 2007
Posts: 6971

Fri Feb 20, 2009 7:48 am quote
sounds like you're doing the right procedure. Are you asking if this is the way to do it, or are you saying you've done this and have no spark?

If you have no spark, i'd start by making sure you don't have the last green wire plugged into the CDI ( the kill-switch wire ) when you do your troubleshooting. More often than not, a lack of spark seems to be caused by issues with the kill circuitry rather than the engine's electrical system.
Hooked
1997 T5 Classic
Joined: 26 Dec 2008
Posts: 186
Location: Durham UK
Fri Feb 20, 2009 7:55 am quote
thanks for the quick reply

i cant get a spark

i havent got the 2nd green wire plugged in

Ive plugged in the stators red/white/green wires into the cdi, ive attached the only wire (except the ht lead) on the cdi to earth and no spark on kick over. Im earthing the spark plug against engine casing

The stator has blue and black wires as well which ive havent connected to anything

Is there anything im doing wrong?
Moderator
1962 GS160mk1, 1963 GS160mk2, 1965 SS180, 1974 Rally 200, wife's LI150
Joined: 05 Mar 2007
Posts: 6971

Fri Feb 20, 2009 8:45 am quote
No, it sounds like you're doing things right. The black, blue and yellow wires are for the bike's electrics ( the blue probably running to a 3 pole regulator ). You SHOULD be able to get it to run with only the red, white and green running from the stator to the CDI to provide spark.

If you don't get spark, it's entirely possible you have a shitty CDI. Do you have another known good one laying around you can try it out on? Or can you possibly try hooking YOUR cdi up to a buddy's bike and see if it provides spark?

I have found that CDI quality lately is absolutely blowful, with them barely lasting a year if they come working at all. I even got a bum Ducati one from scooters originali last year ( they replaced it, of course, being the amazing folks they are) ...it worked for about 5 minutes and then was dead. I replaced it with a "mitsubishi" one and that one died a year later.

Due to this fact of bad CDI quality lately, i highly recommend you carry or keep a spare one around on hand .... if for no other reason, so you can swap it out for troubleshooting purposes like this one. Who knows, having one in the glovebox ready to go might keep you from being stranded roadside some day.
Hooked
1997 T5 Classic
Joined: 26 Dec 2008
Posts: 186
Location: Durham UK
Fri Feb 20, 2009 8:50 am quote
I think you might be right about the CDI

Sadly im the only scooter person round these parts!

As as a final test ill just plug in red/white/green wires and try again? i can leave the wire coming from the cdi (not ht lead the earth? wire) disconnected correct?

Its a mitsubi cdi

Like i said before as well, done resistance check on the stator and it comes back within tolerances. The flywheel can hold a 17mm spanner fine with magnets as well
Moderator
1962 GS160mk1, 1963 GS160mk2, 1965 SS180, 1974 Rally 200, wife's LI150
Joined: 05 Mar 2007
Posts: 6971

Fri Feb 20, 2009 8:52 am quote
yeah, the little yellow wire is just an additional ground thing. They tend to break off after a while anyways. The bike will still run without the little yellow wire connected, but SUPPOSEDLY ( and because of the volatile nature of CDI reliability, i seriously think this can't be proven ) it shortens the life of the thing.

If you subscribe to the Rover Eric school of scooter electrical thought, you can NEVER have enough grounds. The more grounds you have, likely the less electrical problems you'll have. So, attaching the yellow wire is a good idea in the long run.
Hooked
1978 Vespa P200e
Joined: 25 Aug 2008
Posts: 231
Location: SoCal
Fri Feb 20, 2009 10:16 am quote
Hey. Your in the same boat I was in last week.

What I ended up with was just a new CDI and
Luckily for me that was the fix. I bought the
blue Ducati CDI and decided to go that way because
I know what happens when you cut corners.

So now I reccomend to you that you return your
Mitsu one and go with ducati. I also reccomend that
You DL a wiring diagram and follow it to a T.
another thing I did was to get a multimeter and
Check the resistance's between the white and green
And the white and red. Also check to see what's going
On in the spark plug wire.
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