Denso Iridium Plugs


Dec 31, 2006
HP equals heat! IMO, any R3 making over 220 RWHP should be using colder spark plugs to help dissipate the extra heat produced. I use Denso Iridium IX27B, one range colder than stock for the R3. Denso's tiny iridium electrode means no quenching, and actually BETTER durability and conductivity (firing power). These benefits can be also be found in the Denso plug for normal heat range R3s (including triple filter and cam bikes)... the Denso IX24B plug. Highly recommended. :D
220 RWHP !!!:eek: Who other than yourself is generating such power. Research me some plugs I really could use as a stocker. On the same stroke, I too have been drawn to iridium plugs for the sake of longevity. Gear and motor-heads who regularly get under the hood might consider plug replacement on a semi-regular basis. I'd like mine to last for as long as I'm able to ride. Unfortunately I have to do my own yard work and can't afford to hire others to do it. I've no time over the next 5 years.

Jamie: you forgot the [ at the beginning of end /quote]. Oh, and that's not to point a finger. It is to teach a bit of the technique to the less informed.
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Read the end of my post and find Denso IX24B recommended for stock (or slightly modded) R3s. :cool:

There are more than a few turbo R3s, and at least one other supercharged R3 in the USA that I am aware of. These kits don't come with colder plugs and don't discuss going colder in the instructions... they should. :eek:
Jamie: you forgot the [ at the beginning of end /quote]. Oh, and that's not to point a finger. It is to teach a bit of the technique to the less informed.

A finger has been pointed, nonetheless. And, Oh, I don't feel particularly good about sittin' on it :D
One of my many dissertations.......

In retrospect, I've melted a few engines in my time. well not melted them in the liquid sense but melted holes in the pistons from running a little too lean. 2 stroke engines, especially ultra high performance ones are extremely sensitive to melt down so it's advantageous to always keep many heat ranges of spark plugs on hand to tailor the plug to particular conditions. You want a plug to run a tan color with no blistering on the insulator but you don't want a plug to be running dark brown or black. The easiest way to do a plug check is to perform what's called a plug chop. You bring the engine to operating temperature and then do a WOT run and immediately at the end, chop the throttle, pull in the clutch and hit the kill switch. Coast to a stop and pull the plug(s). The read the plug for color. I always ran Bosch Fine Wire Racing Plugs in my sleds as they resist cold fouling and have a good life expectancy. I always stayed away from Split Fire plugs because they tend to flatten the flame kernel (that's what the spark is called) and flame kernel shape is critical in a 2 stroke. When I holed my T'cat (I discussed that in the thread on timing sprockets), the engine was under warranty and I didn't actually melt it due to a lean condition but rather a faulty oil injection metering pump and that caused a big end rod bearing to weld to the crank, break the rod and blow it through the bottom of the crankcase.

I suspect this winter, like most winters, I'll be doing a bit of cylinder re-boring and sleeving as well as piston matching in the shop. Sledders always run their engines at the fine line between reliability and maximum horsepower per cubic inch and it's easy to cross into that grey area of a too lean condition and meltdown.

The more power you extract from any engine of a given displacement n o matter what type of aspiration it is, the more critical heat range of spark plugs become. It's a nice engineering scheme to have underside crown oilers on an engine as that pulls the searing heat of combustion away from the piston crown and takes any localized heating (as in incorrect heat range plugs) and dissipates that heat over a wider area but the heat range is still critical though not as critical as a 2 stroke high performance motor.
I saw Hombres numbers for the Denso IX24B but it's not listed as a Rocket Spark Plug. In fact Denso doesn't list a Rocket III spark plug.

True it doesnt list rocket, but if you browse the catalogue, most of the triumph models use the same plug. Since Hombre lists that plug, its a safe bet it fits:)
"220 RWHP !!!:eek: Who other than yourself is generating such power."

I'm up to about 240. The highest I know of on this side of the pond is Riddicks, which is producing 268 (according to TTS's dyno). I'm waiting for Sam to develop a pipe to fit with my rear sets. I'm hoping to be in the 260s with it once it's been re-tuned to suit the pipe. Since Rid*****and I use the same tuner it's a good comparison. Since dynos are notoriously variable I wouldn't like to compare mine to Hombre's or anyone else's tested elsewhere.

Have you managed to get a slot on your own dyno yet? I've been away for a couple of weeks so if you have, can you point me to the thread?