NC30 loom cdi problems its electrical so i need lots of help

[28hodge]

Went to oulton yesterday and the 10amp fuse in the fusebox that runs the ignition packed up on lap one of session one, not a great day out really. it also somehow managed to take out the cdi at the same time!!!

I have pulled the loom off the bike today unwrapped it all and started tracing it all looking for the problem, which im not finding.

What i have found is a NC35 loom on a NC30 i think.


this shows the CDI having 6 wires coming out of the cdi, my cdi only has 5 wires coming out of the cdi into the black plug
1 to the front coil
1 to the rear coil
1 to the stop run switch
1 to the rev counter
1 to earth

On my loom i have 6 wires coming from the black plug one being a blue and orange as shown on this schematic

on the plug this has no male spade to plug into the cdi so is effectively a dead circuit.
Is this going to cause me problems, i do have a NC30 loom and CDI on the way, am i better off just binning what i now have and fit the nc30 loom. im worried that the nc30 loom wont fit straight in now as something may have been changed to allow it to be run with the 35 loom.


Basically im lost i can see no reason why the bike kept blowing the 10amp fuse in the ignition circuit and then how it managed to spike the cdi and burn it out.

Any help would be very much appreciated

[magg]

IMHO the blue/orange wire in the both the first and second schematics is for the speed limiter input to the ignition control unit. In the first schematic, the blue/orange has a 2k2 ohm resistor connected to it so that the OEM speedo can be removed.

The blue/orange wire/contact on your loom/ignition unit must have a similar termination somewhere.

Have you measured the resistance between the ignition control unit contacts, that normally connect to the black/white (12 volts from run/stop switch) and the green (earth) wires. +ve multimeter lead to "black/white" ignition unit terminal and -ve multimeter lead to "green" terminal. If the ignition fuse has repeatedly blown the resistance should be very low i.e. <2-3 ohms. If resistance is high (>100 ohms) then ignition control unit would not be the cause of the fuse blowing.

[28hodge]

i think i have a uk nc30 cdi which wont have the Blue orange speed restriction wire, i however have a jap wiring loom, the bike is a jap import so thats right, its picked up a uk cdi along the way somewhere which it has now destroyed. the below post kinda explains what i have i think.

viewtopic.php?f=22&t=37868

I will checkthe ignition circuit as you have suggested magg, im rubbish at electical testing but can follow instructions.

i cant get my head around how thw fuse didnt protect the cdi from getting fried i thought that was its purpose to blow before anything more important did?

[28hodge]

I've got the loom here with me on the living room floor, but not my multi meter, just had a quick look, just to check then.

+ve on the red spade connector on the main loom that the rhd run off switch connects into.
-ve on the main green earth that attaches to the frame in front of the front coil.

That right?

[magg]

The fuse does not protect the ignition control unit, the fuse to to stop a fault in the ignition control unit from causing too much current to flow and possible damaging the wiring loom.

Agree that bikes for markets that have no speed restriction would not have a blue/orange wire to the ignition control unit. If your replacement ignition control unit is not a UK version, you will need to do the speed limit mod to the pin that would connect to the blue/orange wire.

I think my instructions are not as good as I would have hoped. It is the resistance of the ignition control unit that should be tested first to confirm that it is the cause of the blown fuse. The multimeter leads should be connected to the pins in the ignition control unit. My reference to the wire colours was only a guide to which pins were to be tested.

If the resistance of the ignition control unit is too low it will blow the fuse. A high resistance suggests the fault is elsewhere.

[magg]

If the ignition control unit proves to be faulty, be sure NOT to run the bike hard ( revved over 2000-3000 rpm) with the new one fitted until you have checked the battery voltage. An over-voltage issue may have caused the old ignition control unit to have failed.

[28hodge]

I'm getting no where fast with any of this, i have set my multimeter to 2000 ohms, and tested the various circuits, im am getting low resistance on all of them, 001 and sometimes 000.

Every circuit from the cdi is fine, every circuit from the fuse box is fine, there is no evidence of buring wires the only evidence of any burning is in the cdi itself which stinks, i have opened it up to try and see whats burnt in there to try and give me a clue as to which circuit has gotten hot, not really helped much.

I have the loom completely off the bike and conpletely stripped of all tape, and nothing seems untoward, the loom has been spliced around a bit as its been modded for the track bike, basically no ignition. its constantly live to the temp gauge so the battery goes flat if the bike is left with the battery conected up.

There is nothing that i can find which would explain why it kept cooking one fuse and then the cdi, unless it was a bad earth by the front loom.

Anything else i should look at?

[CRM]

Loom will be in the post tomorrow pal.
just try that one.
It's not got the headlamp blocks chopped its a complete working loom i removed from one of the bikes years ago

[28hodge]

Cheers Paul, i'll put that loom on and hope that'll be the end of it, but its still bugging me as the why it decided to eat itself, as i can see very little wrong with it.

The A123 battery cell that i made could have put too much voltage through the system and killed it, but i managed to blow the fuse again after returning from halfords with a standard battery, so that kinda rules out that theory.

[magg]

From your description of the condition of the ignition control unit, I would say it has failed. I would expect there is low resistance between the pins of the ignition control unit that connect to the black/white and green wires and this is causing the fuse to blow, no matter what type of battery you use.

If this is the case, there will be nothing wrong with the loom as the fuse did its job.

Are you running total loss or a charging system? If you are using the on-board charging system, has the rect/reg failed resulting in high a voltage that could have caused the ignition control unit to fail. The high voltage mayl not have done the battery any good either.