hesitation/lag from idle to 4k

i have a 83 kz750.I'm getting a hesitation from idle to 4k rpms. If i slowly roll the throttle its fine but if i go 2/3 to full throttle there is a couple of seconds lag then around 4k it pulls like crazy up to red line.Ive took apart cleaned the carbs twice and made sure all jets,etc where clear. Also the bike idles nice and steady at 1100rpm. Thanks for any input.

Has this bike been sitting for a long time? Roy

I'm having the exact same problem, coupled with sputtering without the choke on. Everybody is pointing me to tearing down the carbs and ensuring that both the pilot jet and main jet are good and clean. Try running it at half choke or even full choke to see if this helps. It would definately indicate a carburation problem. If it doesn't, it might simply be not getting enough fuel even to the carbs, but I doubt that's the case if it runs well after 4k RPM. Hope it helps!

May be two problems. 1)clogged pilot jets, 2) fouled out pilot screws. first thing I would do is to remove the pilot screws and clean out the openings with carb cleaner. Make sure that the little holes in the bottom are clear. Seat and open the screws back to the specified amount of turns. If you are running pod filters, open 1/2 turn more. If this will not work than pull the boles and clean out the idle jets. IF there is a plug over these jets, make sure that it is snug in its hole and that it is even there.

Pods?

are the pilot screws the screws on top of the carbs ?

comppro2k7 wrote:

around 4k it pulls like crazy up to red line.

That shows your main jets are clear and they are the correct size. That is the range where the vacuum pistons are up and you are running wide open on the main jets.

comppro2k7 wrote:

I'm getting a hesitation from idle to 4k rpms.

The pilot jets and vacuum piston needle position are primarily responsible for this range. I would clean the carbs and make sure the pilots are clear. Also, check the jet size.

If the pilots are clear and the right size, play with needle position last. Raising the needle a notch will significantly increase throttle response in the 2k to 4k range. If you go too rich, it will bog down in the mid range.

how many turns out from seat for the pilot jets ? mine are at 1 1/4 turns out, the manual says 2 turns out but its for non us spec.

update: i took out the pilot jets cleaned them then cleaned the holes out making sure they weren't clogged. i then tried it 1 turn out, then 1 1/2, both made bike rev worse, so i put it back to 1 1/4 like it was, so would that rule out the pilot jets or should try 2 turns out or more ?

comppro2k7 wrote:

how many turns out from seat for the pilot jets ? mine are at 1 1/4 turns out, the manual says 2 turns out but its for non us spec.

On my 750 twin, the pilot screws run about 2T out. Note, mine are fuel screws so farther out means richer. If yours are air screws, further out means leaner.

according to the manual, they are pilot screws, they are on top where the carbs go into the intake boots to engine. So maybe i should try say 1/2 turns out or 3/4 ? here is a pic for example