Slight acceleration hesitation?

[PegasusIII]

I have a 93 GS500.  upon acceleration, the bike accelerates smoothly from a stop, slightly hesitates around 4k rpms, then accelerates smoothly right after.  it does this in every gear.  ideas anyone?

Pegasus~

[jeremy_nash]

carbs could be dirty, or need rejetted.  how many miles? valves been checked?  any mods to the bike? such as air filter, muffler, or ignition advancer?

[PegasusIII]

carbs could be dirty, or need rejetted.  how many miles? valves been checked?  any mods to the bike? such as air filter, muffler, or ignition advancer?

28k miles.  air filter is clean.  valves havent been checked.  no mods that i'm aware of.  just bought the bike a few weeks ago