I am looking at some cheap and easy performance parts for my yamaha exciter and i was wondering do the air filters like the ones from k&n for snowmobiles really help all that much over the stock airbox?
Yep, BoonDock is right about the jetting. My brother bought a tricked out Mach 1 that had some sort of pipe and those cone style filters on it. It melted down, we rebuilt it, it melted down again. Without that airbox it really leans them out. That 670 Mach 1 was by far the fastest sled I've ever been on, it was scary fast. They really go like a bat out of hell running that lean! But 50 to 80 miles before melt down wasn't very much fun for him. His problems made me a believer in leaving the stock air intake system alone.
first off the K&n filters aren't a "cheap mod" I believe they are pretty pricey. Second the sled will run like garbage and possibly blow up if you don't tune the carbs. It should in my exp. run lean at idle(hard to start when warm) so you have to play with the pilots and or airscrews lean through the midrange(c-clip adjustment) and depends on sled in the top. My 650 actually ran richer without the airbox in the top, what this told me is my airbox actually pressurized the air and gave a slight supercharging affect(very slight i might add, but still usefull).
I would focus of modding the airbox and not replacing it. There is no power to be found for the most part by removing it for filters.
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