Carby slides... Whats the point?

Can someone please explain what the slides in my zx250 are for.

i turned the throttle a little and they dont move, but i can push them in and out. why have slides when you have a throttle butterfly anyhow?

They're operated by vacuum. Basically they are there to compensate for the change in air pressure when you open the throttle. The way they do this is by regulating the speed of the intake charge, hence the "constant velocity" moniker.

These carbs don't have an accelerator pump which is what compensates for mixture changes due to throttle opening on most cars.

notice the needles comming off the bottom of the slides? they dip down into the emulsion tube, and the slides lift under moderate to wide open throttle in the midrange... adjusting the height of the needle adjusts how much fuel you get in the midrange too... towards the top end the slide is pushed up all the way so that the needle is no longer affecting fuel flow

And they work bloody well too.
Smooth out the difference between what you THINK you need and what the motor CAN handle.
Going from Vacum's to EFI is always a bit of a shock due to its RIGHT NOW reaction.
Flat slides will do the same thing, these give you total control of the "slide" and if you dont get it just right you can end with a an awful Buuuuuuurrrr noise and not a lot of power

interesting to note that when yamaha went EFI with their R1's & R6's they kept the throttle slides to maintain a similar style of throttle response

heres a pic of a set of EFI R6 throttle bodies:

gixxers use two pairs of throttle butterflies, the first is user controlled and opens as fast or as slow as you please, the second one (after the injector) is controlled by the ecu and basically performs the same thing as the slides do in carbied bikes. It takes into account engine speed, air velocity, throttle position (tps), and all those other variables to change the secondary 'flies smoothly.

What about KTRIC ? What is so special about them ?

KTRIC is just a throttle position sensor on the carbys that it uses to adjust timing with the CDI depending on how wide you have the throttle open