Alfadave, If you run it uncorked there is no flat spot in the middle, but man is it loud. Try to quieten it down though and the middle goes.
LawManNV, I was given jetting specs from Big Gun which were for the YZ. They didn't even know what came stock in the bike until I told them. They first told me to go to a 180 main until I told them that 170 was stock (they thought 175 was stock) then it was, "well, uhh, try a 175 main." With a 175 main the bike wouldn't get over 45 mph, so I dropped it to a 172main, better but still not good. Went back to stock 170 and the top came back but the midrange was still absent. Then I began the needle adjust boogie.(Spent about three hours this past Sunday) Adjust, go ride, adjust, go ride, etc. The midrange is still not with me, but its rideable. Oh, let's not forget that pilot jet! BG said to go to a 45 pilot. Tried it and the thing kept stalling very easily in first. I finally went back to the stock 42 pilot and my bottom was normal again. I haven't touched the fuel screw because the thing ran so great with the stock pipe and always started easy.
I am at a loss here. Don't know what to do!
Any help from you four stroke gurus would be appreciated.
Coop
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2001 WR250F