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jetting Question!!

2256 Views 5 Replies 2 Participants Last post by  vettepin
I have a 2004 Foreman 450S looking for a close starting point on the jetting. Upgrades Include: .020 high comp wiseco piston, stock cyl. head, hmf Utility slip on, k&n air filter and 2" SNORKLE. (performance package from atv outfitters). I installed the 138 main for starters. Wot seems to be close. Extremly lean in the mid range, clip in bottom groove, even added washer under needle to richen a touch and still lean. Touch the choke and it takes off.

Back in my racing days we use to change the needle with more taper to richen the mid range. I'm not sure where to get a different needle for this carb.
any Ideas?

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well #136 is what i would use. but the needle should be around the middle if you have jetting right .how do you check for lean at mid trottle ?
i used a dyno to see .
plug chop, but also touch the choke it takes off, carb has been cleaned and float level checked. no air leaks anywhere. just tried the 140 main still lean in the middle
well you might be reading the plug wrong, does the bike bog or stumble .i have a stumble at 1/8 throttle and but the plug is right on .
i would lower the clip to where DJ tells you and run a #136. i have dyno sheets with a DJ#140 in and with all my mods it was still running rich, so i dropped to a DJ#138 and it runs the same but a little more perk. i messed with the needle while tuning and it didnt do much to the air/fuel % . so i would go with a 136 or 137 cause your not running a big cam and the other mods and go with that . or maybe your choke is sticking.

ALso are doing this in N or while driving the bike.??
I'm using 138 oem jet stock needle. It is lean for sure in the mid range way before the main has any effect. you can choke it or tape off half of the snorkle and it runs great. Does The the dj needle have any more taper then the stock needle to richen in the mid range?
Back when I use to jet for raceing you would change needles (more or less taper) to richen or to lean out the mid range.

i though you had the power kit with the DJ kit installed ? the jet numbers are a little different for a oem needle and DJ jets. but i would think it should not be runnig that bad .the needle is different but i dont know what is different on it . is the plug white ? maybe give the pilot a turn out .
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