Those settings, in general, should be good. Slightly rich. perhaps.
Can you describe how you determined that it was too lean at the normal setting of a 142 and the second clip?
Proper setting of the idle mixture screw varies from bike to bike. 1 3/4 turns out is a good starting place, but fiddling needs to be done to get it right. Usually this is done by turning the screw out until the RPM peaks, then bringing it out just a bit further. By doing this what you should have found is the slightly lean spot where RPM is the highest. It will probably stumble a bit when hitting the throttle, so turning it out a bit more richens it up so that it is correct for idle to about 1/4 throttle. You want to play with this to find the spot that has the highest RPM, yet doesn't stumble when the throttle is opened. You may have to go back and forth with the idle mixture an the idle speed screws until you find the happy spot.
But again, what lead you to believe that it was lean at the recommended settings?
Tom, first of all thanks for your detailed reply!
Two Bros pipe is wide open compare to other exhausts. So I started with the KLX recommended settings first. clip on second slot, 142 main and two turns out. With this setup pickup was not good and lot of decel pooping. So I turned the fuel mix screw out to 2.5 turns and felt little better pickup and popping was almost gone but still not great so turned it out to 3 turns.
At 3 turns out, No popping and pickup was much better and I liked it. But from mid-range throttle position to wide open throttle bike was struggling. Pushing it beyond 60 mph didn't feel good throttle didn't feel smooth at all compared to stock bike with stock pipe. So I tried clip on 3rd slot and notice noticeable difference in mid-range but still it didn't like it when i push it beyond 70 mph lot of vibration and throttle felt heavy. So I changed main to 145 and and it was all good.
But I wasn't sure how to set the fuel screw perfectly and find sweet spot. I tried this trick: increase the idle speed to 3000 and then turn fuel screw in until engine stumbles and then move out until rpm stop rising then stop and turn it 1/4 out and set the idle screw. I noticed when fuel screw was completely closed (all the way in) bike was still running it was surprising because it should die! also when i turn out the fuel screw it dint raise rpm like after 1.5 turns so set it to 1.75 and it felt better at that settings.
So 145 main, KLX needle with clip on 3rd slot and air screw 1.75 turns out was my final setting and it running good even though i dint test ride it beyond 80 mph .
Two days ago I wanted to see if my settings are rich enough and if I need to do L mod. So to verify i opened air box window and rode for a day....didn't feel much difference but sound was better (deeper and throaty) but next day I notice something happened from 1/4 throttle position to wide open, exhaust sounds horrible ..don't know how to explain but sounds like phrrr phhrr and (no thump! ) and also decel popping!
So closed the air box door but still exhaust sound is same and little decel popping. Fuel screw is 2.5 turns out but it some(very little) decel popping is still there !
It runs good but i can feel it that something is not good but cant figure out what.
Dont know what i did by opening air box door or if its something else?!