6pole ducati stator purple wire problems

[gio695]

Hi,

My name is Gio, and i've been on the forum for a while, but i don't post much because of time (sorry for that)
I've worked on a number of Lambretta's (or engines) but never had this problem and it's driving me mad!

The Lambretta in question is an 1966 Italian 150 Silver Special. I've rebuild the engine but kept as much original parts as possible (also original paint etc).
The ignition is the original 6 pole Ducati, 6V, no battery!

I've been having a problem with the lights that work with the ignition switch in position 2, so the speedo bulb and bullet type lamp (position light?) and rear light.
The Lambretta starts without a problem, first kick every time with the key in position 1 or 3 (headlights etc)
but as soon as i put the key in position 2 it cuts out.
I've checked everything and even changed the complete wiring loom, the ignition switch and the light switch, just in case... al ground cables and lamps are also new.
The problem seems to be the purple wire coming from the ignition!
If i put the brown cable in the place the purple needs to fit the speedo bulb and bullet lamp work!
If i put the purple cable in the position the brown has to be, the bike cuts of with the ignition switch in position 3!!

So, before you say change the stator....i already tried with a second one i had!!!
This is the weirdest problem i ever had.

Is there someone that had the same problem? Or does the Ducati 6pole stator have a known issue with the purple wire?

I've checked everything else a million times and tried everything i know...always same problem!

If i forgot something, please ask.

I hope someone can help me.

[HxPaul]

Get(borrow or buy)"Stickys second edition Lambretta manual" The complete spanners manual.It has all the wiring diagrams at the back,yours is on page 267.

[garry inglis]

were is your earth for the speedo bulb is it the old way on the adjustment screw what i do is solder a 6,wire to the side off the holder fit a ring connection and earth it under one of the throttle rod bolts works a lot better and i would do a continuity test on the purple wire

[gio695]

Hi,

HxPaul, I have sticky's, i also know the wiring diagram inside out by now
Also all electrical wiring is new, so is the ignition switch and light switch.
All bulbs are new and have been checked and replaced just to be certain.

I checked continuity on purple wire AND also changed it with another one as a test,
but problem stays the same!
That's why i'm baffled by this, it's just too weird...

Garry, Earth on speedo bulb is as original, so i will try an extra ground tomorrow, you never know...

Thank you both for helping me eliminate sources.

[firekdp]

You have a PM.

[gio695]

junction box is new, even changed it twice and checked all connections.
bulb holder where cleaned all connections and even changed place for purper wires as a test to see connections worked.
yesterday i even changed the coil with the purple wire for a third one of another stator and another flywheel. Made an extra ground for the speedobulb and changed the two small lamps again...no luck yet!

[Monty]

First of all when you go to the 3rd position does the engine cut out eg the same as turning it to position 1 OFF. or is something else stopping the engine running. disconnect the green coming up to the headset from the coil. I suspect the colour coded wires from your ignition switch are not doing what it should, Start with a meter on position 1 what's connected, should be the earth with a spade that goes to ground and your green or find the colour that you have. That should stay connected continuity wise on all switch positions bar off. then you can move on to the others

[gio695]

Monty, at position 3 the headlights high/low etc all work perfectly.
At position 1 only the brake light (and engine off course)works as supposed
At position 0 the engine cuts off, also correct.
When i connect the brown wire from stator to the purple wire (for position 2) from the switch the speedo bulb, bullet light and brake light just work whithout a problem.
If i connect the purple wire to the brown wire (for position 3) from the switch the engine cuts off.
So i'm pretty sure the problem is the purple wire that comes from the engine that for some strange reason cuts off engine.
Yesterday i noticed that when i give enough revs (throttle) the speedo bulb and bullet first light up and after a second of two the engine cuts off. At normal idle revs (or slightly higher) the engine cuts off immediately.

I will try disconnecting the green that comes in to the switch to see if it's the pink ground (with spade) that makes the engine cut off in position 2 or if it's some other ground.

Thank you

[gio695]

I've changed the flywheel for a third time, also cleaned all grounds and checked sparkplug gap once again and now all is working. I think both flywheels i used had same problem (to little magnetisme?)
But now i have some kind of knock/trembling sound coming out of top end. I hope its the flywheel thats slightly out of balance and notthing else broke .
At least i now know how to fix the purple wire problem.
Thanx to all for your help.
this topic can be closed
Grtz,
Gio

[Adam_Winstone]

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