My gs has a laggy throttle response at high revs . When changing up it takes a momment to react  and the bike starts to slow befor accelerating once again . Carbs have been cleaned  and the floats set and for a while there was no issue but this has crept up , gradually getting worse . There is normal power and it will belt along happily and if i use the throttle progressively it can be smooth but if i want to go for it I get the symptom mentioned ... Hope someone has a clue , I have never balanced the carbs  so I wonder about that? The diaphrams looked good when i checked and i replaced some carb internals though not all ...I did not change the  needles or the pilot jets as they looked ok .

With no other information I would begin to look for a vacuum leak. Maybe the intake boot o rings. Something is causing the slides to not come up, I would guess.

Could also be low floats, failing petcock, kink in a fuel line, carb drain hose facing forward, etc.

Thanks Mr &2, Ive ordered the intake boot o rings .. gotta start somewhere ......

The hesitance is a symptom of poor fuel flow, so along the same lines as what Mr72 said, it could be vacuum but it's worth checking the float heights (5 min check with some transparent tubing) and carb breather hose.

ok< going to take that advice as well and check the float levels with pipe  .i watched a video on this  but dont know where the fuel should rise on a gs500 , does anyone know ... cheers  folks

About the join on the float bowl to carb interface.



This side is slightly too high.

Also note they are slightly tilted on the bike so one end will read higher than the other.

Thanks for that , That will help

Agreed on checking the float levels.  Especially if it's been a little while since the carbs were done.  It's not unheard of for them to self-adjust some.  All it takes is a bit of aquarium air tubing (or similar) and a screw driver.  "Ideal" fuel level is just at the bowl gasket.