My Ninja 250's revs stay up and slowly go back to normal while riding. Where's my problem?

Question

OK, here's my problem in a nutshell. First, my '04 Ninja 250 takes an obscene amount of time to start from cold. When it finally starts, the revs go up to 3,000RPMs and slooowwllly go back to the normal idle speed, even with no choke applied to it!

The, while riding, the revs stay up for a long time and then slowly return to normal WHILE SHIFTING. For example, shifting from 1st gear to 2nd at, say, 4000RPMs, as soon as I press the clutch, the revs stay at 4000RPMs for a few secs, then the engine speed slowly decreases. It does that in every gear, at every RPM range (shifting from 3rd to 4th at 6000RPMs, the engine stays stuck up there and, again, slowly comes back down). It also does this when I am stopped and in neutral, when I blip the throttle up to any RPM range, it stays up there for like 3 seconds and then it settles to normal idle speed. I already had the carbs and fuel system professionally cleaned, but problem remains. What could be my problem? Thanks!!

Answer 1

If there is no problem with throttle cable, A hanging idle is a sign of the engine running lean, check that the carbs are mounted tight, If the carb boots (the rubber pieces that connect the carbs to the engine and airbox to the carbs) are tight. If they are tight who ever cleaned the carbs missed something I'm assuming thats why you had them cleaned originally

Answer 2

Maybe you need to lube the cables and/or the twistgrip..

Answer 3

It sounds as though your throttle cable is sticking.  You are going to have to lube the cable.

Answer 4

suond like a problem with the throttle cables sticking. check them out. probably the push cable. one pulls the carb open the other pushes it closed.