Yesterday my father purchased a 99 yz 400, the thing is like brand new but it has been sitting for almost 5 years!! Today we took the carb apart and i couldn't believe all the build up etc.. I clean it all out, took out all the jets and the float, needle etc.. and got it all cleaned out. We put in fresh gas, we replaced the spark plug etc.. and it fired up with the choke on. I let it warm up and then went to push the choke in and off it went. I opened the choke again and it fired up and I rode it down the street, while riding I pushed the choke in again and sure enough it died. Any suggestions? With the choke on the bike rips!! and all is great but I know something isn't 100%. Any advice would be GREAT!! Thanks guys.