boggingand stalling

[ROBTEA56]

2001 250 yamaha idle rough and stalling when i throttle up. can anyone help.

[99yam40]

you may get more responses if you give a lot more info.

Model # is the 1st thing
and then what has been done so far and a better explanation of what is happening

[ROBTEA56]

bogging and stalling

thank yam40 for your reply more info mod. sx250txrz , we have cleaned the vst and checked fuel pressure it is 35 psi. took out injectors to clean . but they look pretty clean. the manual says to do volt test on the os. sensor gray to blk. 0.6v. when heated any one done this test i must be missing something how can it have voltage when not hooked up.