Coil compatibility?

[Magua]

I've got a new coil for my bike, but unfortunately the wire colours of the new don't match with the old. Trial and error or am I going to fry something if I connect them up wrong?

1980 cb400n btw.

[tri boy]

Post if it's a genuine coil or not, and the primary wire colours.
Is it second hand? Off what?
Is it for your CB?
Throw the team some info.

[Magua]

Non genuine coil, new. https://www.davidsilverspares.co.uk/parts/part_28546/
Black and black with a white stripe on the new, one green and one yellow on the old. For my 400, cb400n 1980.

[tri boy]

The colour coding on your new one could be difficult to decide upon.
Can you email the supplier?

Other option would be to use a multi meter to check wire resistance between it, and the coils iron mount/base.
ie: 4-5 ohms would indicate primary winding wire.
0 resistance would indicate system earth wire.

[Magua]

The colour coding on your new one could be difficult to decide upon.
Can you email the supplier?

I guess I'll have to, damn it. Out of curiosity, what would happen if it was wired up backwards?

[tri boy]

Probably still work, as it is just a winding of copper around a iron base to produce an electric field. Might fail prematurely though.
Try the resistance check first.

[Magua]

Try the resistance check first.

Is that for the new coil?

[xwhatsit]

Do they have polarity? The ignition coil on both my RS and the C50 just has one wire, and it gets earthed through the bolt hole. It's obvious to tell which is the spark plug side, there's no wires there.

So why two wires? Is it an earth return or is it a coil for both cylinders?

[Magua]

Do they have polarity? The ignition coil on both my RS and the C50 just has one wire, and it gets earthed through the bolt hole. It's obvious to tell which is the spark plug side, there's no wires there.

So why two wires? Is it an earth return or is it a coil for both cylinders?

I really have no idea, electrics confuse the hell out of me. Mr David Silver should have included a simple diagram :@


Is that for the new coil?

I'm getting no measurements, I'll attach it to the bike.

[tri boy]

Is that for the new coil?

Yep
10chars

[Magua]

Yep
10chars

No reading, tried all the different resistance levels. There's some sort of coating on the base, scratched a bit away, no difference. I take it you mean to measure between these points? Terrible photo, terrible camera _b

[tri boy]

My useless attempt to pass info on is only making it more confusing for you.
Sorry about that.:Oops:
Probably easier to email the suppliers.:yes:

[Magua]

Lol, thanks anyway.

[The Pastor]

No reading, tried all the different resistance levels. There's some sort of coating on the base, scratched a bit away, no difference. I take it you mean to measure between these points? Terrible photo, terrible camera _b
another mag speical photograph.

[Magua]

"The BLACK-with-WHITE is (+), goes to the IGN circuit (power). The other goes to the points."

I got that from another forum. Though, I don't have points :P

Both wires run to the CDI, the green ones appears to split into two after the CDI, one running to the altenator and the other to the ignition. The Yellow passes through the CDI before splitting into three wires and running to the altenator.

On that basis I'd assume it's black with white (+) to the green?

I'm still waiting to hear back from Davidsilver.

[Magua]

Coil connected. Once started the bike seems to work (I only ran it to work and back), but it's a bitch to start, really doesn't want to. Tried it with the wires plugged in both ways.

[xwhatsit]

Coil connected. Once started the bike seems to work (I only ran it to work and back), but it's a bitch to start, really doesn't want to. Tried it with the wires plugged in both ways.
They haven't supplied the wrong coil, have they? Kind of sounds like it. David Silver is supposed to be pretty good (I wouldn't know myself, you've ordered from them much more often than me) but you hear stories on UK forums about them mixing up models on occasion.

[Ixion]

Is it definately a CDI coil? Or conversely is your bike definately CDI? Not everything with no points and a black box is CDI

CDI coils run off a much higher primary voltage. So a non CDI coil in a CDI circuit may be feak and weeble. Conversely a CDI coil expects a much sharper voltage spike, so a CDI coil in a non CDI circuit may also be feak and weeble

[Magua]

Definately a CDI bike. The Coil box says in vivid "P coil 250/400n", but there's nothing written on the coil itself (from memory), I'll go take another look.

[Magua]

No writing on the coil. I had an umbrella open and drying behind my bike, it just shot it across the length of the room with a backfire trying to start the bike.:crazy:

[Magua]

Received an email from davidsilver. It can be wired either way, yet it wouldn't work either way on my bike. Assuming a faulty product, they sent me a new one, and again it wont work. It doesn't want to start, and when/if it does, it dies as you try to rev it.

If this is the correct part, then what could be the issue? Could I potentially have fucked up connecting the spark plug caps to the leads (was rediculously difficulty to do)?

[Ixion]

Hm. A pertinent question might be : WHY did you get a new coil?

[Magua]

Hm. A pertinent question might be : WHY did you get a new coil?

The search for power. I replaced my jets, needles, float valves etc. Worked well, could sit at 100 in top gear finally, hell, I could even cruise at 120. :0 It didn't last, sometimes I'd have power, sometimes I wouldn't. I assumed this to be an electrical problem, due my electrics sporadicly dying (like they did on the learner ride late last year).

My manual said to look at the ignition system for power problems. I've got a little spark plug tool that checks the power through the leads, told me that the right lead is down on power versus the left. Tried to get a measurement with a multimeter, but it wouldn't return any readings.

So I went fishing again and got a new coil + leads for $50, but now I can't even get it to stay started!

[Ixion]

Well, the problem on the learner ride was a straight forward crappy connection. Nothing to do with the coils.

I'd be somewhat distrustful of "little spark plug tools". Unless there was evidence of misfiring, I'd be more inclined to suspect the CDI for power loss (if indeed it was anything electrical at all).

I'd suggest replacing the original coils. If the hard starting etc goes away then the new coil is probably unsuited to the machine.

From the sound of it these are generic Honda coils. Is there another Honda twin rider who would volunteer his machine to test the coils ? (An IL4 might also work, I don't know if the Honda IL4s have two coils with a waste spark or not)