i just bought a 86 250r atv like 3 days ago 2000 even. it starts first kick everytime but when i ride it it hesitastes real bad. some times it will take off but i cant get it right? i got 40 to 1 gas mixture, new spark plug, cleaned out the carb/adjusted it a 1/4 turn each way. this didnt help any ideas  

I have an 85 tecate 250. My GUESS is that there is still junk/dirt getting into the carb. If you notice that it sometimes floods gas out the carb overflow than there is probably dirt still getting into the float valve/bowl. I put a cheap inline fuel filter and the cleaned my carb and fuel tank at the same time. If you have dirt in the fuel system you will never get it jetted right and will keep having problems.