My mother in law just inherited a fourtrax 300 and it had kerosene put in the gas tank and it was started. I drained the tank, and lines. I washed the tank and lines out with gas and drained them again. It now starts and idles but when I give it throttte it sputters and want to die unless I let off the throttle then it will return to idle. Gonna try new plug tomorrow. ANy other ideas

 

Take the carb bowl off and clean the main jet. Also make sure full fuel flow is getting to the carb and the float/needle/seat is ok.

 

new to this thing do i need to take the whole carb off to take the bowl off

 

I would. I like to take a real good look at things when I work on them.
Might also want to check the valves.