Bike Bogging down on me

Hey. My I decided to take my old 1990 Yamaha Virago out to see how it ran before I started to try and sell it, but then whenever I put on the throttle more than halfway the bike would start to bog down and eventually die if I kept the throttle going that high. It runs fine other wise. What do you guys think could be the problem? I know im not flooding the bike...I think it might be something with the carberator. Alright thanks.

check air filters and for a fouled plug