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859
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12/5/2007
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Lisle, IL
US
Fantasy
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So, I got this bike for a steal. Bike has very low hours, less then 30, all stock except for an FMF pipe and silencer. My problem is with the jetting and idol. I cant seem to get the jetting right. I went with what FMF has recommended for the pipe and year, and thats a 400 MJ and 40 PJ. I feel like it loads up and is running very rich. My air screw was 1.5 turns out as well.
Does anyone have any idea whats going on??
Does anyone have any idea whats going on??
FYI - I tested with many pipes when these bikes 1st came out & the FMF Fatty was by far the worst performer IMHO. It was a mid-range pipe as it concentrated the power in that part of the powerband.
One of the main issues is the oem S-9 nozzle that came on the 02-03 CR2 mikuni's. Honda changed it to an S-7 (2 sizes leaner) on the 04-07 models shorter version tmx equipped with TPS.
I tried a JD kit as well & didn't like it so I went back to the oem needles. His kit back then came with an S-4 so it shows you how much leaner he went with the nozzle. He has since reconfigured his needles a few yrs. ago to work with the oem S-9 from my understanding.
I picked up another 07 cr250 last week and will be doing a bunch more testing with that carb and bike soon. I'll test it back to back against my 07' cr250 equipped with a 38mm PWK.
I owned an 03' cr250, but have since lost my notes for that bike with the TMX carb. I believe I used an s-7 needle jet, along with 1mm removed from the slide cut away. I think they came with #5 slides. A 32.5 pilot the stock needle and a 410 main.
The low end seems to be ok, but wont open up mid and top end.
The Shop
Below are PC's recommended jetting specs. Just choose the yr. & it will show the 02-03 using a stock oem S-9 & the 05-07 using an S-7. https://www.procircuit.com/jettingspecs3.htm
The S-4 nozzle in the JD kit back then was recommended for the 01-03 TMX. Same needles were also used for the 04-07 short body equipped with TPS.
JetsRus still has nozzles available for the mikuni's to be able to fine tune the carbs.
Scroll towards the bottom of the pg. & it will be the 633 series nozzles for the 01-03 TMX Mikuni.
http://www.jetsrus.com/a_jets_by_carburetor_type/needlejet_jets_mikuni…
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