Can you tell us what's been done to the bike? Anything recent like pulling the snorkels? Sounds like the bike is running lean. Mine used to bog at 2500 right after I pulled the snorkels under the seat. The only way to get rid of it was to richen the mains or put the snorkels back in.
If yours started suddenly check for a cracked air box allowing more air into the engine (has the bike backfired recently)? Also check the intake rubbers between the air box and the carb for cracks or deterioration.
One other thing, there is a vent hose that vents the carb bowls. It starts between the carbs and ends up in behind the engine and is right beside the tank vent. If this hose is oriented a certain way, it can cause a syphoning action in the float bowls that restricts fuel flow through the main jets (less atmospheric pressure pushing down on the fuel in the bowls) causing a bog at speed, crosswinds and even when trying to pass tractor trailers. Ask me how I know!!!
