'03 450EXC Jetting

[john_bilbrey]

Dad's '03 450EXC looks like it could be running a little lean, as it is turning the headpipes blue. Not as bad as I've seen on some streetbikes, but there is a definite blue tint to the first several inches of the pipes. It does wipe off when you wash it if that makes a difference. He also gets quite a bit of deceleration "pop". Motor is stock. Any guidelines or baseline recommendations?

 

[Shaw520]

The factory jetting on these machines are generally lean, start off by raising the needle two notches,(lower the needle clip). Your bike will thank you for it. More performance can be had through jet/needle changes,(if you like).

 

[sloopy]

how do you lower the needle clip? just adjusting the fuel mixture screw out allittle wont do it? my 450 seems as if it runs to lean also. i asked the guys at the ktm dealer when i bought it and they told that was a four stroke characteristic. i have only had 2 strokes up till now.

 

[Shaw520]

Adjusting the idle/mixture screw will not help. Remove slide from carb, pull out the needle, lower clip two notches, re-assemble.

:)

 

[sloopy]

ok i did that and it deffinately seems to help and it was alot easier than i thought. thanks