Topic: Ignition Coil Vocabulary

[cb544]

SO... Here we are. Hey guys and girls, not necessarily in that particular order; thanks for being here.

I recently bought a '74 CB550 and have begun the rebuild process. I'm going over the bike with a fine-tooth comb, rebuilding as I go, cleaning and whatnot... which brought me to discover that the spark plug wires are spent. Obviously, I could drill out the old wires and mock up some generic wires (if my Dremel were here)...

I will try to replace the wires myself to save money, however I'm skeptical after the little "digging" I did do within the coils... my question is, what am I looking at for replacement coils?

I realize that I need two coils, each with two outputs... I've found Dyna, and on eBay there are a few keywords which I don't understand. "Single fire", etc... and I'm unsure of the proper resistance (I'm assuming 3 ohm, but have also read that 3 ohm is too much without a resistor installed somewhere between it and the ignition modules.

I've also noticed that OEM NOS coils are as hard to come by as ants' teeth... I've found them in the UK, but perhaps Dyna is better quality? and I'd rather not wait a month in shipping time!

Also, if I do go for the Dyna coils, which wires should I go for?

I realize that this topic has probably been covered before, but I've searched this great site without finding what I'm looking for. I'm sure I just haven't realized which keywords to search for.

Thank you! if only for reading...

[Inigo Montoya]

You have a 550, you want 5 ohm coils. The 550 charging system is a bit weak and the 3 ohms do not always play very well.
Dyna is a common coil to get. they work good but may not come with wires. You could also get any style of dual fire coil you want that is 5 ohm, pretty much.

[cb544]

You have a 550, you want 5 ohm coils. The 550 charging system is a bit weak and the 3 ohms do not always play very well.
Dyna is a common coil to get. they work good but may not come with wires. You could also get any style of dual fire coil you want that is 5 ohm, pretty much.

Brilliant! Thank you very much- that clears it up for me... except the single/dual fire. Does that mean that one or two sparks, respectively fire at the same time? As in both outputs on a single coil fire at the same time, then the other coil fires, as opposed to one cyl. firing from one coil, one from the other, the second from the first and so on... i.e. 1-2-4-3 as opposed to 1&4-2&3 in the "dual fire" coil...

[Inigo Montoya]

On that, I am not sure. I would think that a dual fire would have 2 leads to fire 2 plugs. I could be wrong though.