The `98 500 Fuji engine is supposed to run the RN3C plugs. The crossover to NGK is the BR8ES plug. The BR9 is too cold for that engine. I have had bad luck running NGK in a Fuji engine.
I would go to either BR9 or the RN3C and it should help
Well my triple came with champion RN3C, had way to many problems with them so i changed to NGK BR8ES and my fuji engine runs great with them. Of course i have a triple, so i dont know if that makes a difference or not.
Back to the subject at hand. First I would change over to the BR8ES and see if that helps. If not, I would rebuild the carbs plain and simple. Now from the sounds of it you probably just need to clean/adjust your air jet or air screw. But i would start with a good carb cleaning and go from there. I would be willing to say that that will solve most of your problems.
Polaris is my way out - Other people just use a door.
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