You motorcycle could be bogging down at full throttle or high speeds for a few reasons. Fisrt is the bike carburated or fuel injected. If it is carburated then the air fuel mixture could be off. Or the float in the carburator could be stuck.
Well I would guess that if it only occurs at high speed then it is either fuel or ignition related. The fuel system might be restricted cause a lack of fuel need under load. The ignition may have a misfire only occuring at high rpm.