I just acquired a 2000 bear tracker 250. I starts like a dream no choke needed. Carb was a mess. I cleaned it and ser the needle to the second clip. Runs better but still missing a lot of power. It has great compression (120+) but still feels flat. Won't go across a farm field above 3 gear and that is a struggle. The plug was black with soot but oil looks good and it does not smoke. Waiting to check plug condition now that carb is installed with better settings. I know a 250 isnt a powerhouse but this is missing a lot of power. Also my rectifier leads are really messed up. They are all connected but the insulation is melted. I look forward to hearing suggestions to get it running right.

 

Any one?

 

Rectifier leads, check they are not shorting against each other or to earth and check that the voltage stays between 13v and 14.5v across the battery with engine running.

If the plug is sooty, either you set the needle wrong, or the choke is sticking, or the air filter blocked. Could also be a previous owner fitted a wrong jet. Electrical misfires can also cause a sooty plug, but carb is the most likely.