Ultra Fine Jetting

Questions and Answers about the best carb and Head mods available for the KDX.
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TWMOODY
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Ultra Fine Jetting

Post by TWMOODY »

I have seen different methods of jetting and have a question for the
fine tuning.
On my 05 200 with a RB mod carb,CEK#3,FMF rev,DF3 I am now running
40 pilot and a 152 main.
The bike is RESPONSIVE, no bog, hard hit 1/4-1/2 throttle and by the
seat o the pants feels perfect, however.......... oh yea, no spooge too

From idle to 3/8 throttle if putting to a trail after a short while starts to
sputter (rich) until you crack the throttle a couple times then cleans right up.
It is not noticed at all in the trails. Plug chop at 3/8 throttle shows a totally
black plug.
WOT plug chop is fine.
I have read that you set the AS to the fastest idle first then adjust to response. If the fastest idle is over 2 1/2 turns go down pilot size.
The fastest idle is with the air screw OUT of the carb. With the
AS all the way in the idle is about 850 then keeps going higher until it
is actually out of the carb at 3300 rpm
RB says do not adjust for the fastest idle!
Does anyone think going to a 38 pilot is to thin ?
#2 on the needle gives a bog.
This was tested last week at 60 degrees at 750'
Do I try the 38 ?

No 60 degree weather this week.......SUCKS
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bradf
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Post by bradf »

Beins you have a RB carb I would find the SSS first. That should be between 2 1/2 and 2 3/4 out. The SSS is actually a very precise seat of the pants indicator. It should be adjusted to find the 3rd gear roll-on smooth power delivery point. Fastest idle is not considered. If that is above or below the "normal" range then the pilot should be changed. But you can still tune the pilot in the orignal AS adjustment range of 1/2 to 1 1/2 turns out. If this is out of range then a different pilot would be needed.
'04 220 w/'01 KX250 USD forks, '02 RM125 Showa shock, Rekluse EXP 3.0, LHRB & all RB'd
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