Ok, I just got the '05 WR450 back together. Re-jetted and added a new pipe (Pro Circuit Type 496). The bike was torn down for a frame paint job and re lubricate all bearings etc. Anyway, it fired RIGHT UP! But I noticed a lot of smoke from the pipe while running. I shut it off and smoke billows from the exhaust like a chimney for several minutes after shut down. No internal motor work was done. Only an oil and filter change. The motor sat in a box for a week or so but the intake was taped off. I don't like this smoke. I ran the bike for an our or so before taking it apart. It did not smoke like this. Any of you wise TT types have any ideas?