Ok....here are some rough 'guidelines'....not sure if I mentioned this in my tuning sticky guide...
the 04/05 machines run a carb that is not as 'sophisticated' as the later model FCR's.... so, you kinda have to 'fudge' with the jetting as you would a similar 2-banger machine. Each of the jetting 'circuits' will overlap one another, just like on the FCR. But, the FCR has adjustments in the acc pump circuit (leak jet) that the 42 keihin does not...probably why the 42 came with an adjustable needle....
Ok....the 'typical' way for adjusting the pilot is at idle and off idle... old school way is to simply richen this circuit up by turning out the pilot screw (fuel screw on 4-stroke) or by turning IN the pilot screw (Air screw on 2-stroke)... then, at idle speed, LEAN down this circuit until you reach maximum RPM...then richen this circuit by about 1/4 turn. Now, that makes for a perfect IDLING and easy starting machine... however, it will often cause a BAWG on 2-strokes and machines w/o an adj acc pump circuit. So, you usually have to either increase the fuel in the Pilot circuit (larger slow jet or richen the fuel or air screw, depending on 4stroke vs 2stroke).... another alternative is to richen the needle position....OR, usually, a combination of the two... I can say that on most two strokes, the needle position is USUALLY what you fatten up to compensate for a bog when stabbing the throttle.... Once you have adjusted your fuel screw (4-stroke), if it is too far in (less than 1 turn out) you want to go with the next size SMALLER slow jet. If it is too far out (more then 3 turns out) you want to go with the next LARGER slow jet. And continue to adjust accordingly... just the opposite for 2-strokes because they USUALLY use an AIR screw. when your all said and done, your gonna have a machine that is not tuned PERFECTLY in each circuit, but has been adjusted to work at it's best, given the ability of the carb. With the FCR it is far easier... just tune the pilot circuit using the 'fast idle' method... and if there is a bog... simply adjust the leak jet... or needle....or both, to compensate.
there...clear as mudd... jmho...g
**06 450ER**... #3 (Dale lives on)
86TRX250R (mostly stock 66mm bore x 72mm stroke) **for sale**
86TRX250R (ESR310 72.5mm bore x 72mm stroke '298cc' fully modded) **SOLD**
88TRX250R (ESR330 77.5mm bore x 74mm stroker '345cc' fully modded)
HRC kit (all but gone)
Hot Cams stage III
Okie porting w/ATP CV4 springs (36mm Ti/31mm)
Venom/KBR N2O Porting w/KW springs (37mm/31mm)
Venom/KBR 487 100mm 14.25:1 piston
Cold Fusion Nitrous**
Venom 'QP' pipe
ESR Pro Series pipe
ESR modded intake w/RAT stack
42mm Taper-Bored FCR
Direct Drive clutch lockout, CR500 springs
GT Thunder-Link w/Durablue Lowering Link
Durablue Anti-Sway Bar
Modded shock mounts
Rage Modded Tranny
Jetting/Carb: #168, #45slow, NGPR needle 3rd clip, #55 Leakjet, Pilot 2 turns out.
Jetting/N2O: 22N/21F (22hp)
*STU Comp Cut 21x12x8 (6) paddle 'Padla Brats' on Douglas Blue label 8x8.....
Thanx to: Venom/KBR (Mixxer/Kam), Rage ATV (Dee), Sredum (Chris), and many ORG members