Alternative coils

[pinholenz]

Help me out here please if I am wrong.

The Haynes specification for an OEM coil for the XZ are
Primary resistance: 2.7 Ohms
Secondary Resistance 7.9KiloOhms

I have just pulled a coil from a donor bike and the measurements are
Primary resistance: 3.0 Ohms
Secondary Resistance 8.3KiloOhms

That indicates to me that its a healthy coil. I.e if the Secondary resistance were below 7.9 KiloOhms then I would have a problem. resulting in a lower spark voltage.(Orange colour, not blue)

So the OEM  R1 Stick Coil Specifications are:
Primary resistance: 1.91- 1.61 Ohms
Secondary Resistance 8.5- 11.5 KiloOhms

This would indicate to me that the spark voltage from the OEM R1 Stick coils will be much healthier (higher) than from the OEM XZ coils. I assume thats a good thing. Am I right?

In my case I run Iridium plugs which have performed faultlessly.

If you are interested in reliable riding, (rather than having a totally OEM bike), is there any reason not to use R1 stick coils instead of a bolt-onto-the-frame OEM look-alike?

[The Prophet of Doom]

is there any reason not to use R1 stick coils instead of a bolt-onto-the-frame OEM look-alike?

I get twisted around by electrics, but wouldn't nearly halving the resistance double your TCI current?.
Whether or not you let the magic smoke out you will only know through experimentation.  Have you got a spare TCI?

[kevin g]

Yes, the lower primary resistance will require that the TCI provide more current to the coil.  The current would be about 14V / Coil resistance.  The charging system supplies more than 12 volts when running.  The TCI transistors are pretty big and may handle it.  If anyone knows what transistors are used in the output you could look up the data sheet.  I think I saw that information somewhere.

The voltage output from the secondary coil is dependent on the ratio of turns of wire between the primary and secondary.  If the ratio is 1000 turns the output voltage would be ~14,000 volts.  This does not take into consideration parasitic resistance in the circuit.

You cannot tell coil output from resistance.  The diameter and length of the wire are both factors.  A smaller diameter wire with the same number of turns will have a higher resistance.  More turns of the same diameter wire will have more resistance but would provide a higher spark voltage due to a higher turns ratio (keeping the primary coil the same).

[pinholenz]

Fortunately I do have a spare TCI. Thanks for your concern POD!

Bernd Knechties in Germany has helped me track down the originator of the use of the Coil Stacks in XZ's. His name is  Jurgen and he did use Coil Sticks from a 2004 Yamaha R1. ( I see no reason why other years would not work as well). Bernd (Aka Ernie) says the second adopter is Dennis Lagopodis from Greece. Dennis bought an XZ in Germany and rode it home to Greece.

I spoke to Dennis via video link last night. He confirmed that it is an easy fit. The Coil Stick sits up taller than the regular spark plug cap. The same orange wire that comes from the TCI to the OEM  coil joins up to the orange wire on the tail of the Coil Stick wiring. The other wire goes to the other terminal.

I will give it a try in the next few weeks. If it works OK then it will be a handy alternative to our OEM coils.

[injuhneer]

This is interesting. While researching the ignition of the XZ I have found statements indicating it is transistor controlled and others that it is capacitive discharge. The coil specification for each is different.

The ~3Ω is typical of transistor systems. The R1 measures to be lower on the primary and higher on the secondary than the XZ coil. I have seen a broad range of values for CDI coils. The Hella CoP units have a spec of 0.3Ω-1.0Ω primary and 8Ω-15Ω secondary.

I suppose the good news is that these R1 coils can be run by the XZ ignition module!

I have a handful of the Hellas on hand. I am wondering if it would be worth testing them on my bike.

[Walt_M.]

I'm not sure who said it is cdi but the Vision definitely is TCI. 

[injuhneer]

It is cited as CDI in several of the articles from Cycle in the Resources.

[cvincer]

My usual ref for ignition problems:-

ridersofvision.net > technical > Dave's Ignition FAQ

[pinholenz]

Hi Mike,

The Haynes workshop manual refers to the "igniter" as a TCI unit. Since Haynes manuals closely follow the manufacturers workshop manuals, (which POD has made available on this forum), its a safe bet that this is all XZ's run a  Transistor Controlled Ignition (TCI) and not a Capacitor Discharge Ignition (CDI). Hence the reference to "beefy" transistors in the postings above.

I think Cycle has got his terminology mixed up if he was talking about the XZ's ignition system.

Cheers

[The Prophet of Doom]

If it was CDI it would have a fairly sizeable capacitor in the box.  It doesn't.
Can't be a CDI without the C

[injuhneer]

If it was CDI it would have a fairly sizeable capacitor in the box.  It doesn't.
Can't be a CDI without the C

True enough. I haven't cracked one open and as such didn't know (why I asked).

[MikeScoot]

True enough. I haven't cracked one open and as such didn't know (why I asked).

It's not too tricky to pull apart but you need a good solder-sucker or solder soaking ribbon to free the pins that connect to the connectors moulded into the case. Once the pins are all desoldered it comes apart pretty easily - but you have to wiggle the heat-sinks a bit to get them out of their slots. You'll see what I mean when you open the screw-on cover.

Melting or cutting an access hole in the other side is NOT a good idea in my opinion as there would be too much risk of damaging the innards.

[The Prophet of Doom]

Melting or cutting an access hole in the other side is NOT a good idea in my opinion as there would be too much risk of damaging the innards.

I couldn't agree more. 
De-soldering the pins is easy enough, and if you don't have the skills to do that, then you sure as hell wont have the skills to fix it once you've cut open an access hatch.

[fret not]

Yeah, words have meanings.  I recall in the 50s going to a "coke machine" to get a soda.  It was common terminology to use "coke" to refer to any soda.  In the 70s when I was working in a dealership CDI ignition was just becoming common.  Remember the Kawasaki Blue Streak?  3 cylinder 500cc 2 stroke screamer.  Our mechanics were cautioned specifically about the possibility of stopping a heart from the discharge of the ignition system.  CDI became a 'universal' term for electronic ignitions, but CDI is a specific type of system, among others in the 'electronic ignition' group. :police:

[injuhneer]

I do understand the difference. One system accumulates energy in the coil. The other accumulates in the capacitor. One uses field collapse to generate high voltage. The other using a pulse step-up transformer.

Indeed. Words aren't always used correctly. One of my favorites is the juxtaposition of "tolerate" and "condone" in contemporary media but I digress.

I asked the initial question about type to determine which coil type was needed. Now that CoP is common there are dozens of coil models for automotive applications that are inexpensive and can be purchased new.

I appreciate the leg-up on the research gents. :-)

@ FretNot - I lived in Sherwood Forest when I was a youngster. I see you are in Grass Valley. My dad was a general foreman during the Oroville Dam project.

[fret not]

I am familiar with that neighborhood on Old Auburn rd.  Rural yet close enough to town.  I am a bit farther out south of there, east of Lake of the Pines a couple miles.  FIRE SEASON is here and I still need to cut some trees near my buildings.

[MikeScoot]

Glad you other Mikes know where each other is (are?). I have no idea where you both are  - other than that it is way too far for me and my chainsaw to be there before dinner tomorrow night - or even the night after that.

[injuhneer]

Glad you other Mikes know where each other is (are?). I have no idea where you both are  - other than that it is way too far for me and my chainsaw to be there before dinner tomorrow night - or even the night after that.

I live about 15 miles from Tombstone, Arizona. Less than a mile from Fort Huachuca, Arizona.

[fret not]

Tombstone, Arizona desert country, for sure.  A bit hot this time of year.  Warm enough here in the Sierra foothills (36 - 38C), I can only imagine the heat in Arizona.  I used to live in the desert but developed an affinity for anything green, so now I live in the woods of northern California.   

[pinholenz]

Hmm, news here in New Zealand  today was that the hottest place in world, Death Valley, reached its highest temperature in 100 odd years....

But I digress. Today I jury-rigged a Coil on Plug from the R1 on to one cylinder of the XZ550.

Before I started, I had a spare TCI unit from an XZ400 so I did my testing with that rather than risk frying my main TCI
With a sparkplug in the CoP and the bike turning over on the starter, I had a very healthy blue white spark from the CoP.
When I put the CoP on the sparkplug in the engine, as the starter was turning over, the starter clutch slipped and caught again with a hell of a bang. (Igniting before TDC?) Then a few turns later the engine ran.
I guessed that the timing of the spark wasn't right (or that there were multiple sparks) or maybe I had hooked up the LT leads round the wrong way. So I swapped the LT leads over but got the same result.

Happily the bike started as normal (without any bangs) when I reverted to OEM running again.

So, The trial worked, but it didn't quite work the way I hoped. The guys on the R1 forum say that the spark at the CoP is  triggered by a negative (earth) pulse from their ECU.

So can some Guru tell me which terminal of the CoP would equate to the Orange lead on the XZ OEM coils.

The two wiring schemes seem to go something like this. (But electrics do my head in - I could be wrong)

XZ Positive from TCI is Red, this becomes Red and White from the connector to the OEM coil.
XZ "trigger" from TCI is black or grey (depending upon which cylinder) and becomes Orange from the connector to the OEM coil
R1 Positive from ECU is Black and Red directly to the CoP
R1 "trigger" from ECU are various colours depending which of 4 cylinders it feeds, directly to the CoP.