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03 400ex pilot screw help

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14K views 4 replies 3 participants last post by  my5sons  
#1 ·
Hi i recently cleaned out my carb. What i was wondering was it says in my clymer that the initial opening is 2-1/4 and final opening is 1 turn out. what is this (initial and final)????..On my cr125 it is just how many turns out from the seated position... can someone please help???thanks
 
#2 ·
Did you count the number of turns before you cleaned the carb? Because if you didn't, then what the 2 1/4 and 1 turn out is...

Initially the pilot screw is 2 1/4 turns out, turn the throttle screw until you get 1,400 rpms, then perform the idle drop procedure. Once you get the idle drop procedure down, it's 1 turn out after that. I believe most people just do 2 3/4 turns out. Hopefully someone who has experience with it can help. I'm surprised the Clymer manual doesn't tell you that.
 
#3 ·
I always just set the pilot screw to the initial setting and then warm the engine up to normal operating temperature and then fine tune the adjustment to get the best idle.
 
#5 ·
Yeah, and most everyone here doesn't have one. Many of them just go by sound. Not me, I can't do that, so I just go with what works for me! :) That's why I gave you the 2 3/4 opening.

If you want to fine tune it, here is the procedure from the manual:
IDLE DROP PROCEDURE

NOTE:

The pilot screw is factory pre-set and no adjustment is necessary unless the pilot screw is replaced. Use a tachometer with graduations of 50 rpm or smaller that will accurately indicate a 50 rpm change.

1. Turn the pilot screw clockwise until it seats lightly, then back it out to the specification given. This is an initial setting prior to the final pilot screw
adjustment.

CAUTION:
Damage to the pilot screw seat will occur if the pilot
screw is tightened against the seat.

INITIAL OPENING: 2-1/4 turns out

2. Warm up the engine to operating temperature. Stop and go riding for 10 minutes is sufficient.

3. Stop the engine and connect a tachometer according to the tachometer manufacturer’s instructions.

(If you really want the tach, www.rockymountainatvmc.com has an hour/tachometer for $43.00) Most of the reviews say that the tach is only good for initial setting, but that's exactly what you need it for! :) )

4. Start the engine and adjust the idle speed with the throttle stop screw.

IDLE SPEED: 1400 + or - 100 rpm

5. Turn the pilot screw in or out slowly to obtain the highest engine speed.

6. Lightly open the throttle 2 - 3 times, then adjust the idle speed with the throttle stop screw.

7. Turn the pilot screw in gradually until the engine speed drops by 50 rpm.

8. Turn the pilot screw out to the final opening.

FINAL OPENING: 1 turn out

9. Readjust the idle speed with the throttle stop screw.