Try a DR9EA NGK
And the Info if you run to your local Auto Parts or ATV dealer
•Thread Diameter: 12mm
•Thread Reach: 19mm ( 3/4")
•Type: Resistor

 

I have a four pack of dr9's on the way, should have them tomorrow or the next day. nobody local had them for me darnit. then there's the Jr mentioned by Viper, and DSNUT is gonna get back with me on the plug # he gets from HPR, and now also the champion OMR recommends. I will see how easy can find the champion, that'll prolly be an easy one to grab, if the dr9's I got show to be too hot still.

thanks alot again everybody!

Hey one more thing - why a resistor plug on the DS? or any quad for that matter? all my 3-wheelers always used DR's too....but we got no radio or anything to interfere with?

 

I used to ask all the time also and was told because of the CDI Champion Spark Plugs

 

Hightower.I have one of the #10 NGK plugs that i got from HPR and the # is NGK-1299-JR10B.Hope this helps.

 

Thanks, that matches Viper's number as well!

 

I just use stock ngk plugs, but what OMR said makes sense. When I used to ride 2 strokes, Champion gold paladium plugs were the only plugs that didnt' foul out all the time. NGK are cold plugs, good for pollution standards no doubt. Even though I have a brand new ngk set, I will switch back to Champion plugs just remembering the difference in performance from before. When I have a choice in auto stores, Champion plugs seem to last much longer at better performance than other plugs for EFI truck too. I have only changed plugs/wires twice in 170K miles in 94 Dodge Dakota, still running like a champion (using Shell gas helps too).

 

From the champion site:

At the moment the spark jumps the gap it causes a high frequency burst of energy, this is known as RFI (radio frequency interference). This is why Champion introduced resistor spark plugs in the mid 1960's. Placing a resistor within the spark plug suppresses the RFI. Without resistor plugs in your car you can experience static on your radio as well as interfere with other sensitive electronic equipment. Some later model vehicles as well as newer Powersport engines must use resistor plugs for a proper "talkback" to the electronic ignition. Outboard marine Capacitive Discharge Ignition (CDI) such as used on some Johnson and Evinrude marine engines require a special inductive type resistor (such as a Champion Q-type resistor). Use of non-inductive resistor type plugs on these motors can cause misfire and poor performance.
For automotive CDI high output ignition systems systems (such as Mallory, MSD, Crane and Accel), refer to Resistor plugs for race engines for information relative to modified motors.

Fouling is when the spark plugs firing tip becomes coated with excessive fuel, oil, or combustion deposits so that it is unable to produce a spark. A plug can become fouled from continues low speed driving, improper spark plug heat range (too cold), improper timing (over-retarded), too rich an air/fuel ratio or an oil leak into combustion chamber. A variety of self-cleaning features are designed into most plugs to reduce fouling.

Heat range

The term spark plug heat range refers to the speed with which the plug can transfer heat from the combustion chamber to the engine head. Whether the plug is to be installed in a boat, lawnmower or racecar, it has been found the optimum combustion chamber temperature for gasoline engines is between 500°C–850°C. When it is within that range it is cool enough to avoid pre-ignition and plug tip overheating (which can cause engine damage), while still hot enough to burn off combustion deposits which cause fouling.

The spark plug can help maintain the optimum combustion chamber temperature. The primary method used to do this is by altering the internal length of the core nose, in addition, the alloy compositions in the electrodes can be changed. This means you may not be able to visually tell a difference between heat ranges. When a spark plug is referred to as a “cold plug”, it is one that transfers heat rapidly from the firing tip into the engine head, which keeps the firing tip cooler. A “hot plug” has a much slower rate of heat transfer, which keeps the firing tip hotter.

An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate racing fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug. A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase. In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber.

The heat range numbers used by spark plug manufacturers are not universal, by that we mean, a 10 heat range in Champion is not the same as a 10 heat range in NGK nor the same in Autolite. Some manufacturers numbering systems are opposite the other, for domestic manufacturers (Champion, Autolite, Splitfire), the higher the number, the hotter the plug. For Japanese manufacturers (NGK, Denso), the higher the number, the colder the plug.

Do not make spark plug changes at the same time as another engine modification such as injection, carburetion or timing changes as in the event of poor results, it can lead to misleading and inaccurate conclusions (an exception would be when the alternate plugs came as part of a single precalibrated upgrade kit). When making spark plug heat range changes, it is better to err on the side of too cold a plug. The worst thing that can happen from too cold a plug is a fouled spark plug, too hot a spark plug can cause severe engine damage.

Based on this info we should be using a "Q" type plug since we have CDI's.

Look at the site, there is a chart that shows what all of the letters and #'s mean so you can decide which plug you want to try.

Ben

 

NGK does make a iridium plug. You might want to look into them too. This is the part number for the 9's. DR9EIX They do make the 8's as well. I have the ngk spark plug symbol chart if it helps you more.

 

I run the JR9B and 650Viper runs the JR10B. The 10's can be bought from HPR and the 9's I get at my local street bike shop (they are ment for big bore street bikes). I run 11.5 to 1 with nitrous and the 9's seem to do the trick just fine. Viper runs a bit more compression and nitrous so he runs the 10's. Both of thes plugs have a considerable larger grounding strap so they seem to stand up to more abuse.

 

I have been running the dr8 iridium for several years now.
I may go to the cooler heat range iridium, but not til after I confirm exactly what heat range I need, cause iridiums are pricy.
However, THEBOM advised me to run standard plugs and not iridium. Not sure why, and also looks like HPR promotes standard rather than iridium too. maybe the higher heat of high performance motors is harder on the tiny electrode? you'd think they'd be fine, if they are made for the specified heat range.
I've always liked the dr8 iridiums in my previous motor build for the past several years. I have never dynoed the difference in my bike, but a friend of mine claims the dyno same day testing showed a 2hp gain just switching from standard to iridium on his 400 trinity cheetah banshee. he has been running them for a couples years now, never any fouling issues out of the norm.