i currently own a 09 yz250f with athena 290.
The problem is when i ride at steady rpms(which can be as 1/4 or even 1/2 or even 3/4 throttle opened) the bike is not possible to ride. It's so annoying... As if someone gives and takes away my throttle every second. If i twist the throttle the bike responds amazingly, no bog, no hesitation of any kind. When riding in the woods is not a problem but when on fire roads - arghhh. I have taken off the carb but didn't check it, clean it or see what the jets are. Another thing is that it is impossible to start it cold if i dont pull the hot start. Choke on - no chance, choke off - again no chance. Pull the hot start it fires from 1-2 kicks. Also when hot i have to pull the hot start and it fires from 1-2 kicks.
I will take the carb off, clean it and see what jetting it's in. I want to see if there is a rubber on the easy access fuel screw(PO may have not put it). But it will be nice if you can give me some advice what procedures i can do before taking it off for determining rich/lean or which jet to check or riding with choke on/off, hot start and so on... I have tried unplugging TPS but bike lost a lot of power but as far as i remember that sputter went away. I did follow the manual and troubleshooting the TPS and everything was in spec....
P.S. i know that there are a number of topics about jetting but my problem is strange for me because i cant start it normally. Valves in spec.
Thanks! (otherwise it's an amazing enduro bike! Keep that in mind!)
Edited by nk_dimitrov, 28 April 2012 - 10:21 AM.