Topic: aftermarket ignition coils? CB550F

[jason41987]

i was looking at the ignition coils sold with my bike (not installed) and although bolt coils are good... theyre both for cylinders 2 and 3... which seem to have shorter spark plug wires than those for the outside cylinders... so if i have to replace one of these coils, is there any reason at all to stick with CB550 coils which are getting harder and harder to find

i mean.. i have to face the fact that replacement parts for this bike are becoming harder and harder to find, and that if i have to replace something, such as coils, i should start looking for aftermarket alternatives...

i noticed JCWhitney sells an emgo ignition coil that has two spark plug leads coming from one coil... would these work for something like a CB550F?.. and if not, what would?.. is not not theoretically possible to have one coil per plug, two individual coils wired to the same point if i really needed to?, or perhaps convert to a coil on plug solution?.. just hypothetically speaking

but.. im curious if these emgo coils, or something similar would work as a replacement?... would be nice to have a replacement that didnt use fixed plug cables, but rather spark plug cables that could be changed if needed

[IndyFour]

I put these "universal coils" on my bike a couple of years ago from this shop.....it's local but they have an extensive online store.....Go here and scroll down.....

http://www.newmotorcycleparts.com/electrical/coils.html

I replaced the plug caps at the same time.  The coils were a direct fit on my 550k and it was the best $100 i ever spent to make the bike run well and reliably. 

[jason41987]

talking about that coil in the middle of the page for $39.95?.. allows you to have seperate plug wires as well and they bolted to the original coil bracket?

[LesterPiglet]

Coils are coils. If you find something suitable make it fit. Unless you want sandcast. 

[jason41987]

i was just suprised they fit the original bracket, if they really do, its not something i would have expected

[Deltarider]

Coils are coils.

There's impedance (primary) to be observed.
On that site I don't see it specified.

•Comes with 2 long 7mm wires attached 2.8

What does that 2.8 mean? If it is impedance, it's too low and you'll need a balast resistor in the primary lead.

[Killer Canary]

A low cost alternative would be the splicers that NGK make. You could add extra cable to the existing wires, unless you're bound and determined to spend.

[jason41987]

the resistance on one of the coils is starting to get a bit on the high side.. so i was considering scrapping that one sometime in the next 6 months and replace it

[jason41987]

about to order my coils... but curious... umm, how many ohms do i actually need? i believe standard was 5ohms, most of what i find as far as aftermarket ignition coils are 4 to 4.2 ohms... the 4.2 ohm coils are the cylindrical universal dual-lead coils, and the 4 ohm coils are these

http://www.dimecitycycles.com/vintage-cafe-racer-caferacer-bobber-brat-chopper-custom-motorcycle-electronic-ignition-parts-universal-12-volt-ignition-coil-si-165-2.html

im not sure if theyll match the mounting bracket on my 550F though.. maybe, i dont know... but just how many ohms should i be looking for? and what effect will higher or lower ohms have on the electrical system?

[bjbuchanan]

Just search it, the three other posts that are concurrent with this one are all found in 5 minutes of searching using the left toolbar. There is literally an abundance of knowledge on the subject. Check the faq too, there is a writeup on the options.

Search Hondaman posts and TwoTired, they both have writeups on all your questions. That guy Bodi too, but his posts are tougher to find

[TwoTired]

the resistance on one of the coils is starting to get a bit on the high side..

Curious as to how that would happen.
The "coil" is made from two lengths of insulated wire wrapped into coils of close proximity to each other.  The resistance is determined by the length and wire size diameter. 
Failure modes are a break in the wire which reads open or very very high resistance (like infinity).  The other failure mode is where the insulation fails and the wraps of wire short to each other, which shortens the electrical path and LOWERS the measured resistance.

I'd like to know what causes a given piece of wire to change it's electrical properties.  (Besides the very small role temperature plays).

Is there some physical trauma that the the coil experienced, which let in water and corroded the wire's diameter uniformly over 10 thousand or so wraps to make the wire a "bit" narrower in wire diameter?

[K3Owner]

FYI for the OP - I bought a set of these EMGO coils for my 78 550K and they are just fine. A little smaller than the originals so, if you're replacing just one, you will need to adapt it to the frame with some metal strap.

[jason41987]

K3Owner, which emgos are you speaking of? the ones in that link i posted?.. and i intend to replace both... is 4ohms enough or would i still need to add a resistor to these?

[bjbuchanan]

The 4 ohm xan be a little taxing on your smaller 4 if you have a stronger headlight, diff bulbs, non factory current draw. If the emgo actually spec out to 4 ohm i would be surprised tho. I bought 4 ohm and received 3~ and im not the only one to report that. If lower than 4 get the resistor pack.

[jason41987]

im back now... suffered a head injury so i havent been on here or working on my bike much... and ford the record i injured my head walking down my stairs... still never injured myself on a motorcycle ;-)

so... im still inquiring about the coils.. im looking at a few options here...

i can buy the 5ohm dyna coils at about $120

i can get the dual-lead cylinder type coils listed for triumphs and similar bikes at 4.2ohms for around $50 each

or i could completely ignore the ohms, but something else, and add a ballast resistor to it which from what i hear will also pro-long the life of the points..

but which resistor should i use, and i like how the cylinder coils look, but of course theyre stuffed under the tank so it really doesnt matter.. im debating whether i should drop the $120 for dyna coils of if a less expensive alternative is actually better.. and im sticking with points

[Deltarider]

I remember the years that Bosch lanced the "Superbobine" for cars, a (red) 3 Ω coil with a starter switched ballastresistor attached. Theoretical that would be the best in a conventional Kettering ignition if you'd ask me. Think early GL1000 Goldwings, if I'm not mistaking the last breakerpoints equipped Honda's. So if you must buy Dyna's (personally I cannot recommend them), the 3 Ω type coils combined with a 1 - 1 ,5 Ω ballast resistor would be first choice. It's what Hondaman does with his resistor pack. You can also go for the cheapest 4,5 - 5 Ω coil. Believe me: a coil is a coil, no matter what boasting Dyna does.

Now here's a interesting question for the engineers in this forum. If one - ignition key 'on', killswitch in 'run', but battery disconnected - measures 1,5 Ω between the + battery cable and the coil + side (say because of aged wires and connectors), is that as good as a 1,5 Ω ballast resistor?

[jason41987]

when selecting a resistor for lower ohm coils, am i looking to take the primary resistance of the coil and combine it with a resistor that combined will match the 5ohms this bike uses?.. so like 3ohm coil, 2ohm resistor = 5ohm total?

[Deltarider]

I modified my previous post. Let's await answers from the experts.
BTW your suggestion is correct but I would limit to 4,7 Ω total resistance. That is what the genuine coils measured.

[jason41987]

ok, so is 4.7 ohms the optimum i should shoot for, or is it 5ohms?.. or anywere in between 4.5-5?... im thinking theres a good chance ill add the hondaman ignition too later on down the road when i decide to do some more long-distance traveling

[Deltarider]

IMO Hondaman's combination of a 3 Ω coil and a 1 - 1,5 Ω ballast resistor makes sense. If you choose the genuine coil (indeed between 4,5 and 5 Ω) or an imitation you don't want a resistor.