I bought a pretty clean looking 03 WR450 for cheap last month (there may be a lesson here). It was running real ragged but had been sitting up and had a bunch of goodies (recluse clutch, etc) and I figured it probably just needed the carb cleaned. Cleaned the bottom end of the carb twice and it actually ran pretty good with the choke on but immediately went real bad with it off. Took it to a local retired indy mechanic with 20 years of dirt bike experience. He's recleaned the carb twice and says it looks good and checked static timing but without a bike specific service manual he's stumped. He thinking it may be CDI related a this point but hates to buy a non returnable CDI without being sure. I did a search and will tell him to try disconnecting the TPS. What else would you try?