Hi again! how are you guys?!
i would like to ask you a question about a yz 250 '96. A friend of mine has this bike and he is facing 2 main problems:

1. he is fouling plugs
2. he is consuming a lot of carburant (with a full tank he runs 30 to 35 km)

the specs of the carb are the followings:
main jet: 155
pilot: 45
needle:N3VF , 2nd clip position
air:1,5
plug: b7es

does anyone know what we should do to solve this situation??

thanks a lot

Has he done a compression test?
Jetting does not change on its own. More likely the engine is very tired.

he didn't done it yet but we are going to take a look,
we are going also to check the float level.. yesterday he bought a manual online, hope it helps..

thanks for the advice Wiliam