Topic: 78 CB750 Coils/wires/plug caps

[WaleFab]

Heya guys,
I'm replacing my coils as I'm having issues with my OEM ones and the wires that are molded into them, hardening up and cutting out on my cyl 2 (believe there is a fray and crack in the wire)
It usually runs pretty good most of the time, but I just want a fresh setup. Picking up my buddies 3.3 Ohm coil packs (basically the Dyna 3Ohm) he was to use on his XS650, ill be running the 1Ohm resistor in series to each coil as my research from HondaMan on other feeds suggest.

My Question though...
The current setup is the OEM 5ohm coils, with the molded in wires and NO Resistor caps, and non resistor plugs...
if I'm to go with a new Accel wire setup, either being copper core or graphite, by rights i shouldn't need to run the resistor caps either correct?
Only time i saw the resistor caps on a CB was on a 650 of my girlfriends at the time, but that is a CDI system with 2.5Ohm coils

Any insight as to which wire is ideal over the other, and if the resistor caps are needed or not would be great.

At this point I'm likely going to go with the copper core wires with no resistor caps as that's most similar to what i currently have which I know is working but would still like some opinions on the matter... thanks

[flybox1]

IIRC, hondaman mentioned factory setup of caps and plugs had 7.5k ohm total resistance.
someone correct me if im wrong, pls.

[Deltarider]

A Honda mechanic warned me never to use graphite wire.

[Jerry Rxman Griffin aka MuthaF'er]

I'm running 3 ohm Dyna coils with their yellow copper wires without resistors/resistor caps on one and radio suppression wires with no resistors/resistor caps on the other. Dyna III and Dyna 2000 that has the radio suppression wires.

Both of mine do fine. I have just never felt the need to resist my more powerful coils.

I'm thinking the Honda caps are 5 ohm and 10 ohm?   
 

[el pachuco]

WaleFab, I have the same problem that you did/do, with the stiff and cracked plug wires.
I'm not one to reinvent the wheel so I went with stock replacements. A very nice price for a complete, no hassle, no guess work, package.

http://z1parts.net/honda-cb750-ignition-coil-set-k1-k6-30500-300-013/

[WaleFab]

Isn't an XS650 a twin cylinder bike? if so, I suggest you choose different coils.

The coils that are used by the XS is a single input dual output the same as the coils used for our I4s. They are the the "generic" Green Dyna 3ohm oils, so no, it doesnt matter if their for an XS or CB the coil operation is the same

I'm running 3 ohm Dyna coils with their yellow copper wires without resistors/resistor caps on one and radio suppression wires with no resistors/resistor caps on the other. Dyna III and Dyna 2000 that has the radio suppression wires.

Both of mine do fine. I have just never felt the need to resist my more powerful coils.

I'm thinking the Honda caps are 5 ohm and 10 ohm?   
 

What do you mean radio suppression wires? just a better control of interference?
So your running basically "full" 3ohm power to your plugs? To me that seems relatively fine, considering I'll be wiring in a 1ohm in series on the Black/White power wire to each coil...

 

[Jerry Rxman Griffin aka MuthaF'er]

The 'radio suppression' wires as they are labeled apparently is a necessity due to the Dyna 2000 ignition and it's electronics.

Yeah, I'm shooting the whole spark, as I see it, to the plugs. Isn't that what hotter coils are for?! Why throttle them down?! Sizeable draw on the electricals if your system is weak. And that would be my only reason for toning down hotter coils. Before I rebuilt my entire electrical system with new stuff I called Dyna one day about the draw with the coils and my Dyna III and the resulting weak electrical system. We talked about this very issue. He sent me free of charge a ballast they use to tone these down. It's a white ceramic rectangle about 2.75" long by .75" square with 2 spades coming from it with 1.4 ohm resistance. Labeled MO CB30-1R2-J. Perhaps this is the basis for Hondaman's ignition module? 

[Deltarider]

Yeah, I'm shooting the whole spark, as I see it, to the plugs.

You can shoot what you want but your plugs decide with their gaps when, what and how long. Extra energy stored in super-de-puper coils is no use when the plugs don't need it and don't ask for it. Decades ago I went for the green 3 Ω Dyna coils myself and never noticed any difference. The 1,4 Ω ballast resistor you mention is good to limit draw. Why Hondaman made the choice for 2 Ω, I don't know. I suggested him 1 or 1,5 Ω, because the standard Honda coils are 4,7 Ω and you can expect some extra resistance in 40 year old wiring. Back then the socalled superbobines  (bobine=coil) with such a ballast resistor attached (Bosch supercoils were red where the standard coils were blue) came on the market to facilitate easier starting in cold conditions when battery may be wasn't tiptop. Whilst cranking battery voltage can drop as low as 9-10 Volts making things difficult for the ignition. During starting that switchable ballast resistor was bypassed so coils received full power and after start the ballast resistor was switched in and so limited the power that now was no longer needed. That was the idea, it was a trick to create full energy at cold starts under harsh conditions. Nothing special. You can see this wiring on early types Goldwing.

[WaleFab]

Isn't an XS650 a twin cylinder bike? if so, I suggest you choose different coils.

The coils that are used by the XS is a single input dual output the same as the coils used for our I4s. They are the the "generic" Green Dyna 3ohm oils, so no, it doesnt matter if their for an XS or CB the coil operation is the same

My point was there's only 1 coil, not the required 2 by our bikes.  I know they use the same wasted spark, but was most having a bit of laugh at the irony of it.

Haha fair enough, but yes, I have 2 of them.

I'm running the Antigravity XPS-1 battery, the tiny 4cell and have had ZERO issues with it, but slightly concerned in regards to draw on the new coils so it Wouldn't hurt to pick up some 1ohm resistors like these http://www.be-electronics.com/product_p/25w1d0.htm from the local electronics shop, wire them in and also grab a plug wire kit from Mopac and build my own wires without the use of resistor caps.
Cam chain tension and valve gaps likely wouldn't hurt too while I'm in there haha.



I'll post with pics of the final setup and how it works out.

[Deltarider]

If you're interested in how it was on older types Goldwing, here are some pics that explain it. The white ceramic behind the coils is the ballast resistor.