Quote Originally Posted by Danzer1 View Post
You can just change the needle clip height but be aware that jet needle and needle jet only control mid-range power (approx. 25% to 75%).

You can still be lean at idle through 25% and full throttle - 75% to 100%. If you limit your operation at the outer ranges, your temps MIGHT not suffer much (and your plugs and other leaning effects).

If you want to adjust idle - the air screw can usually be adjusted to allow less air (richer) maybe a half to full turn. If still hot at idle (through 25%) the idle jet or as some call it the pilot jet, would need to be changed (this is rare).

If changing the clip position at mid range does not get it to richen up enough, the needle jet is the limiting factor (only so much fuel can get to the needle to atomize it), no matter how far you move the clip. If that's the case, the needle jet would need to be changed (this is rare).

If you run at 75% to full throttle often, the only way to change a lean condition is to change the main jet - no other change will effect WOT fuel delivery.

So, see how it goes with your operating style and conditions. And as Dave says, the only true way to "read" lean/rich is to look at the spark plug. To do that under each of the conditions listed above, is time consuming and the engine must be "chopped" (from the throttle condition being tested - idle, 50%, 100%) down to off to get a good "reading" on a clean, cleaned or new plug.

Also note, the percentages given are approximate, there is overlap, for instance the main jet starts kicking in at about 50%, but provides all of the fuel delivery at approx. 75%.

Greg
582 do not have the lean issues that the 503 does

Most 582 will run 5500 to 6000 rpm which put this in the main need range.

Thee is little power under 75% power