i have a 2003 Honda 400ex that ive had for a while never had a problem with it until a couple of weeks ago and it started bogging at about 3/4 throttle in every gear the things ive swaped are the carb 2 new different spark plugs new coil new petcock new cdi box ive cleaned and oiled the air filter checked the valves I just don't know what to do anymore please help I really don't want to take it to a professional and spend a lot of money I wanna just try and save money and do it myself the mods on it are .440 big bore kit stage 2 hot cams fmf titanium exhaust and k&n airfilter please help

 

Check compression