A/F Screw

How many turns out for an air/fuel screw on a Keihin 24mm carb for a 2009 DRX90

[jerkyboy]

Start out at about 1 1/2 turns out.

Somebody just told me 3 turns

[jerkyboy]

I like to start at 1.5. Its only a starting point it really depends on what pilot you are running and also the weather.

ok thanks

I also try mine at 1.5 turns and try to tune it in at 1 turn.

Thanks for the reassurance guys...I am taking a half day to give it my last best shot...I hope to post some great news later today...thanks for all your help!

Call me if you need any help. Ill try to walk you threw it. Dont be afraid to call and call as many times as you need. Keep up the faith. You will get it.

ok 1.5 urns out and it's running!!! Breaking up a bit on high rev's...half a turn more out on the fuel screw? in?

[riding4fun]

It its idling ok, then move on to the other circuits ,, like the main or needle clip. If it's breaking up on the higher revs I would say main jet.

Do a fresh plug chop.

Thanks...all set...thank you to everyone for all of your help...I will post race results tomorrow

[mxdad423]

you do not want to be more than 2 turns out max on the air screw, the way to set it is start the bike and take it for a ride to get it up to operating temp, at idle turn the air screw all the way in and start backing it back out a 1/4 turn at a time till you get it to it's highest idle, give it about 15 seconds in between each 1/4 turn to catch up to itself, after you acheive it's highest idle shut it off and run the air screw back in counting the turns, the most efficient setting is at 1 1/2 turns out but anywhere in between 1 and 2 turns out is ok. if you are more than 2 turns out you need to go smaller on the pilot jet (leaner) if less than 1 turn out you you want to go bigger on the pilot (richer)If you are breaking up on top end that meens that it is probably the main jet, if it is a fluttering sound than you are probably to rich (need small main jet) if it is a popping than you are probably to lean (need bigger main jet), an easy way to check it is to do a plug chop, get it to operating temp and get it to where you can run it on a long straight away at WOT for a few seconds and pull the teather, pull the plug and check the color, if it is on the white side you are to lean and need a bigger main, if it is blackÂ_ you will need a smaller main, you want to try to get a nice light brown color to the plug.Hope this helps you out, jetting can get very agrivating, but once you figure out what circuts do what it makes it alot easier. Let me know if I can help you any further.


Kevin Smitley

Thanks once again to everyone for all your help...my son took home a 1st and 2nd place trophy...needs some tweaking still but ran great!!!