It will work, but the only differance in the ES and EYA is that the electrode has a v-grove in it. The diameter of the electrode is still the same size, 2.5mm. If you have a problem with fouling plugs you better check your oil pump output or you carbs for being extremely rich. A better plug for not fouling is the EV, fine tip electrode, 1mm plug. They are 3 times the price of a standard plug but resist fouling. Afer talking to several area racers, unless your motor is highly modified and needs a special application plug, your just wasting your money on the more expensive plugs, because you gain nothing in power on a stock sled. Hope this helps. Later.
I agree with Maydaze about the EV's. I used BR9EV's all winter last year and somehow never once did i foul a plug. It could just be luck too. Plus i'm always watching my jetting. Worked for me anyway...
Hotter Plugs may resist fouling, although if you are fouling plugs, as suggested by someone else, you are either running too rich or you are getting too much oil simple as that. A hotter plug could fix your problems if your plugs foul after the engine is running and hot. But if you foul them out while trying to start the engine, it will not help your problems.
The heat range on a spark plug is basic terms is how long the plug stays hot after combustion. If you take a 9 plug versuse an 8 plug it may not be very visable but compare a 9 to either a 7 or a 6 and you can see the difference in the porcelin portion of the plug that surrounds the electrode. One will be longer or shorter than the other. Obviously if it stays hot too long then you may get pre-ignition or detonation.
hope this clears things up just a little bit. I would suggest to clean and/or re-jet your carbs if you are having serious problems with fouling.
Polaris is my way out - Other people just use a door.
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