I am brand new to 4strokes and just getting back into riding after 8 yr hiatus. I have an 02 WR426 and absolutely love it most of the time. It is completely stock with the the air snorkle removed, baffle pulled and the throttle stop chopped (street legal to boot, I've never seen so much attention to a bike rolling through town!). I had no idea how many other trick mods there are for these bike until I found this site! Carby on my 90 CR125 was pretty easy to take apart even for a novice such as myself 8 yrs ago. These puppies look a little bit more involved (TPS, vacuum hoses everywhere) and I am a bit nervous about doing the BK mod that has been discussed in some threads. Now that you know I am no master mechanic I have the following nagging problem. Every so often the bike just spits and sputters like something is totally retarted in timing. Then magically it goes away after many bad words. My buddy has the EXACT same bike and set up as mine and his does it too. It tends to happen more often it seems we have noticed, on pavement when cruising around 50 to 70 (guessing) but it also will occur on dirt. Muggy weather also seems to make it occur more often. I would say it happens between 1/4 and 3/4 throttle but if held WOT it clears up and runs OK until you come back into that same range. Any suggestions of what we can do to clear this up? We live in the NW lower peninsula of Michigan. Altitude is around a 1000ft and doesn't vary more than 800ft +/-. If we want to modify our bikes any further, which order is the most logical of the remaining mods to do for the 426 (gray wire, YZ timing, BK mod, YZ needle and jettings?) We plan on riding probably right until the snow flies and the Skidoo's come out. What will temps in the 30 to 50F range do to our jetting? For the most part they run great and the power is unbelievable. It just seems like there is more potential that I would like to tap into and would like to clear up the stuttering problem. Thanks for listening and any help you can provide.