i would also say repack the silencer. you will probably be suprised at the condition you find it in. i bought my 2000 kx 250 rode it about six times, now i've stripped it down completely. when i got to the silencer i just pitched it some because it was fmf and i'll probably go with a full procircuit system the second reason is that it was the packing was such a mess. although i didn't have bogging issues i had unburnt oil coming out of the expansion chamber = not good.