New pilot jet: Should I change needle and/or air screw

[mlhend1]

New pilot jet: Should I change needle and/or air screw?

I own a 1994 kdx with fmf pipe, lid off, torque ring, carb spacer and fmf silencer. I was running a 42 pilot at with stock needle at the second clip from the bottom (toward long part of needle - rich), and air screw out about 3/4. These were the settings for hot summer (90s degree) weather in North Carolina. Now that it has been getting cooler I have been having to turn th air screw to about 1/4 out. I was told by the Kawasaki deal to try a 45 pilot ( I had a 48, but this made the 1/8 - 1/4 throttle to rich, judging by the spark plug). The mid to top end is still right on (would someone please explain why?). Once I get the 45 pilot jet should I also change the needle clip position and/or the air screw? If so what settings should I try first?

 

[fuzzy]

I take it your lean boggin now? I'd try the 45 ike the dealer said. W/ your air screw still at 1/4 it should be rich on the pilot, so open it up. If it's still lean then try the 48 you mentioned.

The main jet does affect all circuits off-idle but you can more or less think of it as the mid-top jet. Chances are if your not lean-bogging on the top now then you weren't 'spot on' in the 90deg weather like you though.

Hope this helps....I'm not as good as explainig it as some on here, but I can always tune my carb perfect! :)

 

[Canadian Dave]

If adjusting your air screw is doing a satisfactory job of compensating for the changes in air temp then there isn't really any need to change your pilot jet.

Typically lower air temps require adjustments( richer) to the main and pilot jet but depending on the condition of your jetting prior to changes in atmospheric conditions this isn't always the case ( if you were too rich in the first place). Be sure to check the main jet by doing some WOT plug readings as the air temp drops.

David

 

[canyncarvr]

Having an otherwise OK needle too high (you're on clip 4) is going to make you too rich right at 1/8-1/4 throttle.

So..you have a problem between where the pilot wants to run and the taper of the needle starts (too soon).

Sounds like YOU need JDs spreadsheet! But...'til then, if you have a -73 needle, try it on #2 (they are numbered from the blunt end). If you have a -74, try #3.

If you asked, I'd tell you that you can get JDs spreadsheet at:

http://www.jdjetting.com


But that might be considered advertising.......so I won't tell you unless you specifically ASK me!! ;)

 

[fuzzy]

Nice sheet!