Please see my new page on the subject at www.dragonfly75.com/jaguar/intakes.html Having a quality carburetor jetted and sized right makes a ton of difference in how a bike runs. It starts better, idles smoother, accelerates crisper, has better peak power, and doesn't foul plugs. My last dirt bike was a Honda CR250 and my riding buddy had a 250 Gas Gas. We were at 3000 ft elevation and mine was jetted perfectly whereas his was still jetted stock which was for sea level. At that elevation he was running rich and he occassionally had to be pulled back to our cars after fouling the plug. I tried to tell him but he wouldn't listen. I don't see why anyone wouldn't want their ride to be correctly jetted.