Is it really that bad to both have resistor plugs AND 5 kOhms plug caps?
I'm currently using Dyna cables with plug caps, DW-800 Grey silicone, 8mm graphite suppression core with DYNA 5 ohm coils + Hondaman ign + points.
I should not use NGK Iridium plugs with these cables? Or what negative will happen if I use reisitor and 5kohms cables/plugs?
I must use Denso X24ES-U or NGK D8EA with the surpressed wires/caps?
My carb jetting adventure has blackened some plugs. So I need to order some more.
I've learned to never use the expensive iriidium plugs until the ignition and carb float/ jetting are OK (perfect).
Actually, PeWe: that puts the resistance back to what Honda started with in 1967, and kept until the 1975 bikes came out. They used 7500 ohm caps with non-resistor plugs. The resistor-type sparkplugs are about 2200-2500 ohms, so using them with the 5000 ohm caps and the stock coils (1967-1974 types) makes it a long-spark, low-current system again.
The thing most often seen when this Resistor-cap + Resistor Plug setup is applied to a bike that had poor caps and plugs is: it starts a lot easier, especially when cold. This is due to the long-duration spark igniting the cold fuel charge for a longer time. It also extends the high-RPM burn rate, producing more torque at speeds over 7000 RPM. For some reason (urban myths?), people have long thought that the stock Honda system was a "weak spark", maybe because the color of the spark appears yellow when the plug is laid against the head in a spark test (? or something?). But, this appearance is due to our eyes' perception: a short, bright spark appears blue to us, while a longer one has a bit more time to activate our eyes' color sensors (red in particular), which tends to make the spark look orange or yellow. Typically, any arc across a given size gap is going to appear white or blue if very short, or more orange-y if longer. Speaking as an Electrical Engineer who sees LOTs of arcs and sparks in my work (intentional or not!), this has long been my 'view' of it.
In the SOHC4 bikes, starting with the CB500-4 coils, the primary side of the coils changed from 4.6 ohms to 4.4 ohms, indicating a shorter, hotter spark was the goal. The spark energy was then "slowed down" at the plugs by increasing the resistance, making the duration of those coils' sparks about 1.38mS. (This is, BTW, the same as is found on the post-1975 CB750 bikes with the 10,000 ohm caps). The mechanics of how this all works is [painfully] detailed in the Electrical section of my book, and was the sole reason I spent those 2 pages depicting the life-and-death cycle of a single spark from a coil. It itemizes the 'why' behind resistance, and how it can be used to tune a coil-and-plug setup to get the spark you need. Almost every engine benefits from a long-duration spark, but with the waste-spark system we have in these bikes, there is a practical [time] limit of the spark during the overlap cycle (i.e., between exhaust-intake strokes), beyond which it starts to ignite the incoming charge for the next cycle, making it burn up the intake tract toward the carb, causing a "flat spot" in performance (often seen in pod-filter setups). In bikes like the Katana, with its 16k redline, the spark must necessarily be short (or get shortened electronically) above 12000-13000 RPM lest it burn long enough to ignite the 'leftovers' during the exhaust stroke, causing other problems. But, that's all a topic of the 'tana riders...
