idle screw position

[antsx]

Hi how far should the idle screw be out?ec250 07 when i took the carb off to change the pilot i had a look at the slide it was prob 2-2.5mm[guess] gap and when i wound out the idle screw it took 4 full turns to bottom the slide with no gap, does the slide need to be bottomed with no gap? This might be a stupid question but what is the idle srew for? if it should be in a certain position and you set the idle by getting the right pilot and needle? the more i learn about jetting the more confusing it is haha! its all fun tho
thanks ant

 

[Jakobi]

There is no 100% correct answer. With the slide shut the bike will not idle. You want to open it to a point that it will idle. This is dependant on the position of the air screw, the needle diameter, and the pilot jet (as well as the slide cutaway). Its about getting the mix right.

If the needle diameter is too rich you will end up with a small pilot to sustain an idle, and a rich burble at 1/8th throttle before the needle comes onto the taper. If it is far too rich you will have to use the idle screw to lift the slide up too far and you will bypass the straight section and end up on the needle taper. This results in inconsistent idling and the pilot and air screw seem to have very little effect.

I'd say around 2-2.5mm gap should be fine. You can also use the method every tutorial describes to fine tune. Ie once idling slowly open the air screw and see if the idle rises. If it does back the idle down a bit more and continue testing. If the air screw comes out beyond 2.5 turns go a size smaller on the pilot and try again.