NC24 and coil sticks

[advectus]

I'm pretty sure you can do it but need a bit of advice as I don't want to bugger up the ignition module. Can I use coil sticks on an NC24. If so, is there any particular one to use (cbr600rr 2003-2010 seem to fit most old bikes) and do I need to modify any wiring??

Thanks.

[CMSMJ1]

Awaiting our resident NC24 and coil guru, Neo....

Fairly sure you need to figure it out properly and as to the benefits....

[Neosophist]

I'm pretty sure you can do it but need a bit of advice as I don't want to bugger up the ignition module. Can I use coil sticks on an NC24. If so, is there any particular one to use (cbr600rr 2003-2010 seem to fit most old bikes) and do I need to modify any wiring??

Thanks.

Short answer is No.

Providing your stock ignition isn't broken in someway then there is no gain over stock.

The NC24 uses 4 seperate coil packs due to the firing order of the bike it is not wasted spark like a tradition inline 4 or the NC30.

The stick coil conversion works becuase most inline 4s and the NC30 only run two coils, each coil fires two plugs at the same time (wasted spark system)

The stick coils are a lower resistance than the original coils (approximatly half the value) but thats ok if you wire them together as you get the original value or close enough so it doesnt fry your ignition unit.

You also get half the voltage (6v instead of 12) which is a separate issue.

Since you wouldnt wire them together on the NC24 youll end up with less resistance than stock and fry the ignition unit.

Any particular reason why you would want to do this anyway?

[CMSMJ1]

Et voila..

Top skills Mart!

[advectus]

The old coils are bulky and (usually) in the way when I want to work on the bike. The one currently fitted are (obviously) old and the HT leads need replacing. I'm currently fitting cbr600rr coil sticks to my zxr400 and thought it might "modernise" the vfr a little. I guess I could still do it if I fitted series resistors??? to the wiring.

[magg]

If an engine uses individual ignition coils for each spark plug then a stick coil is a suitable alternative provided it does not overload the existing ignition control unit. Have actually reliably run the cbr600 stick coils on the zxr400, an overload issue may not appear immediately.

IMHO double fire waste spark ignition systems cannot use stick coils without significant alteration to the normal ignition control unit. Simple connecting two stick coils in parallel or series presents different but nonetheless significant operating problems.

[advectus]

the zxr is not an issue as the cbr coils will be in series in pairs (because of the wasted spark). This is a tried and tested modification used on many race and road bikes. The obvious benefit for the zxr is when you fit a ram air system as the standard coils have to be moved.

The VFR does not have a wasted spark system and has a separate coil for each cylinder so using a resistor in series with each coil stick could balance the load on the ignition module (see how I'm not calling it a CDI ). By measuring the resistance of the coil and wiring a resistor of the same (or approximate) value you create a potential divider circuit putting 6v over the resistor and 6v over the coil. The resistor will have to be of a sufficient power rating to cope with the current but I believe this could work.


If it's too much hassle to use the coil sticks in the vfr can I just replace the HT leads? Don't have the bike in front of me at the moment so don't know how the leads are connected to the plug caps??? (are they screw in?)

[magg]

Is that how Honda intended their cbr600 stick coils to be connected, as a pair in series? My info has individual cbr600 stick coils firing individual spark plugs via individual drive signals. I have my doubts that a series connected pair of stick coils is the best solution to a double fire waste spark ignition system. Even if it works, halving the current by doubling the resistance will reduce the spark energy by a factor of four. Coil stored energy is a function of current squared.

IMHO I considered the stick coil idea suitable for your VFR (NC24) because it does not have a wasted spark system but an individual coil system.

[advectus]

the coils are designed to use 6v not 12v. this is why they are in series on a wasted spark system. they are only coils of wire so connecting them in series will cause no damage to the coils. The issue with the vfr is that the current coils have 12v supply to each of them, hence individually wiring a cbr600 coil stick to the current wiring without the protection of an additional load balancing resistor will fry the ignition module (as it will draw twice the current is was designed to supply). likewise with the zxr, if you wired them in parallel (which according to guys on the zxrworld forum, doesn't work) you again would be supplying 12v to a 6v coil.

therefore.... on a zxr400 the cbr600 coil sticks need to be wired in series (for load balancing) and on the VFR would require an additional load balancing resistor. in each situation you would be supplying the coil stick with the required 6V and appropriate current and therefore there is no change to the spark energy. the laws of conservation of energy require that energy cannot be created or destroyed but only changed in form and hence you will get the same power out as that to which you put in (obviously owing to inefficiencies not all the energy will be used to create the spark, some will create heat and sound)

lets assume that the standard coils on the zxr are supplied with 100 ohms and are supplied with 12v and the cbr coils are only 50 ohms.

since R=V/I, I=V/R therefore current(A) is 12/100, 0.12A or 120mA

Power = IV, therefore the power consumption of the coil is 0.12 x 12 which is 1.44Watts

with the stick coils, if the coils are in series then they have the same combined resistance as the original coils and therefore the calculation remains unchanged. If you want to continue the maths for wiring them in parallel you will see that the current fro each coil will double and, although will double the power of each coil and give a better spark, is likely to burn out the ignition unit and/or the coils.

Therefore it is likely that the stick coils are suitable for both bikes provided that they are correctly implemented.....which leads back to my original question!

[magg]

The cbr600 service manual available to me has individual stick coils driven by individual signals from the ignition coil unit.
On which model of cbr600 did you find stick coils that were connected in series and why do you consider your cbr600 stick coils to be 6 volt?