I got my 02 426 about 3 weeks ago and for the most part it runs extremely well. The only times I have any problems I have with it is when I stab the throttle up to about 1/2 throttle, the engine stumbles for what is probably one engine revelution, puts out a small puff of black smoke that you can barely see, and then runs fine. I turned the fuel screw in about a 1/2 turn from where my dealer set it. Everything on the bike is stock and will probably stay that way as I am going to college this fall. This is not a real big problem, I was just wondering if I should do the BK mod or take it to the dealer to have them work on the jetting. I do not have any doubts about my mechanical abilities, I can do it easily, I am just not that sure about carbuerators.......see I don't even know how to spell it. Even if I don't like it the BK mod can be undone with no side effects, right.......just remove the screw and it is back to stock settings. Also any help any of yo southern Idaho guys could give me on jetting would be great......I live in Glenns Ferry, about half way between Boise and Twin Falls.