i have a 07 450 er. Only mods are k&n air filter and dyno jet kit. The guy told me he put in a 124 main. I'm not sure what notch the E-clip is on. I also have stock exhaust with the spark arrestor out. So heres the problem....when you give it lots of throttle from idle it dies. Also pretty hard to start sometimes. I'm new at this. I should have just left it alone (stock). Also where should the air fuel screw be set at? I'm at a loss, and I just had surgery, so money is tight. Can't afford to take it to somebody. Any help would be great!!!!!!!!! Thanks.

good thing for you these quads are pretty easy to work on and there are lots of ppl on here to help out

also sorry to say this but i dont like dyno jet main jets they are different size than OEM but there is a chart ill find for you to convert them to the standard OEM jets and for your mods with the spark arrestor removed you should be at around a 150-155 main i believe the 124 is way to small

is the lid on?

heres the chart

also did you realize your i the wrong section? post this in the engine section and you might get more responses

I tried the dyno=jet kit in my 06 an it didnt work so well. Keep the needle a run stock jets. put a 35 leak jet in it and should help with lack of throttle response.

124 dyno jet is WAY too small. Get keihin jets and go with a 165 main, or just jet the HRC jet kit.