Topic: Dynatek 5 ohm coils and Dyna s ignition. Best spark plug to use?

[Knightro]

Hey all.  Im sure this is covered somewhere in the 40,000 + posts but i cant find this topic specifically and ive read about 10 different posts already.  Sorry.  I have a vegicle safety test in 2 days and i need this bike to pass.  I need electrical for it to pass sooo im pressed for time.   

Do i use the standard d7es? D7ea? Fml.  Point is with all these electrical changes im just not sure if the same old plug is the best.  Im sure someone knows. 

78 cb550. Using dyna wires dw-300

Dyna s ignition.

Coils are dc8-1

Also, my stator is reading about 1.1 ohms... some posts say if all yellows are consistent with no grounding issues, it should be ok.   I just dont want to fry this stuff im broke now.  Lol.   

Thanks team!

[dave500]

use the standard plug

[Knightro]

Straight forward enough.   

Thanks. 👍🏽

[TwoTired]

The resistance per spark lead on a 550 is 10k per from factory via the plug caps.  Though 5k per is acceptable.

The resistance is a good thing (to a point), as it lengthens the spark event and prolongs spark plug life.

Cheers,

[Knightro]

Thanks twotired

Is the syator ohms ok?  I modified my original post cause figured out the wire colors ... duh. 

[Knightro]

Stator

[TwoTired]

Stator

while the manual states .35 ohms.  Popular meters don't measure that well for such low readings.

1.1 is likely ok.  Did you subtract out the meter's lead resistance to get that number?

Do a voltage vs rpm test, if you are worried about charging.

Cheers,

[Deltarider]

The resistance is a good thing (to a point), as it lengthens the spark event and prolongs spark plug life.

This statement shows up every now and then. To this day the supposed 'lengthening' remained unproven. In no automotive literature have I found evidence for this claim let alone confirmation. Not that I am not open to the possibility, but I want to see evidence and simply drawing analogies with DC is not good enough, I'm afraid. Also: 'Honda did this, so it must be good' is not my kind of science. I've even seen people draw strange conclusions from Honda's maintenance scedule. Rather I would see a calculation of what percentage of the resistance is benificial for that supposed lengthening of spark duration and what part is lost in heat, because that is what a resistor does by nature. Personally I find that with a total resistance of 20kΩ in one circuit you are too close to where an ignition may become dysfunctional and I advice, what btw every dealer in the land does, to stay with or have 5kΩ. As a matter of fact 10kΩ plugcaps are hard to find anymore and I certainly would not recommend to have both resistor plugs and caps. Why add components that can become a problem? Resistance is resistance and the mere fact that it is in an electronic component doesn't make it any special.

[PeWe]

5 kohm NGK plug caps and non resistor plugs must be fine. NGK is the brand my CB750 always has liked. It use the std D8EA with Dyna 5 ohm coils.
CB500/550 runs on D7EA as I have seen.

A colleague has an Aprilia 650 twin something that had too much resistance, wire + plug cap + R-plug. It ran really bad and no idle.
Had 5kΩ caps + resistor plugs. It should have 1kΩ caps + non resistor plugs. Its coils had very high resistance. Honda is different but this show that it must be correct.

[Knightro]

Thanks all I really appreciate the input.

Too tired yes I did subtract the line to line reading to get that 1.1 on my multi meter

Thanks again!

[TwoTired]

FYI:  All my Cb550s Run 10K resistor caps and non resistor D7EA plugs.  The leads are stranded steel core from coil to plug cap. They have run this way their entire life.

Cheers,

[Duke McDukiedook]

Whatever the standard Denso is for that bike is what I would use.

Denso showed the part as X22ES-U for a 78 550.