running lean?

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cornishwrecker220
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running lean?

Post by cornishwrecker220 »

my 03 220 appears to be running a tad lean just off throttle & sometimes bogs down just when when you want to start a gnarley climb, a few blips of the throttle seems to cure this but it has caught me out a few times.
mid range pull is strong as is the top end but on over run e.g throttle off going down a climb the bike sounds like its running out of gas.
ive stripped & cleaned the carb,measured the float height (which was fine).standard jetting,needle clip 2nd from the top, air screw 1.15 turns out instead of 1.30 (but bog still there)..im running fmf gnarly pipe with power core2 silencer also boysen rad valve with dual stage reeds,i also have the air box lid removed & the jetting is all standard & plug colour is a nice tan (irridium plug)...have tried 3rd clip from the top (needle) but bike ran too rich so put it back on the 2nd clip...im currently running the factory standard 32.1 mix & wonderd if i ran 40.1 perhaps the little bit extra gas & less oil mix would help cure my slight bog by richening the fuel delivery slightly..ive checked for air leaks etc & found none even fitted my standard reed valve etc but bog was still there & it didnt have the pull or mid range kick that the rad valve has..appart from this slight bog the bike runs fine & hauls ass .i havent owned the bike long & my last steed was a 525exc ktm...perhaps it just a 2 smoke kinda thing..what do you chaps think??
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fuzzy
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Post by fuzzy »

Try the air screw in a hair more. If your down to .5turns then enlarge the pilot jet one size. Switching to 40:1 wouldn't be a bad idea either. I like 32:1, but it can make things more sensitive. If your high-rpm riding is light, then 40:1 is still plenty of oil.
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scheckaet
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Post by scheckaet »

lean with stock jetting? they usually run rich even with your mods...
Go there for the right way to jet your bike: http://www.kdxrider.net/forums/viewtopic.php?t=1156
cornishwrecker220
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Post by cornishwrecker220 »

i know every bike runs different but ive noticed the carb on mine seems very sensitive even with the slightest of adjustments..ive read that running a rad valve requires a leaner jetting set up so when i checked on their web site (boysen) they have a jetting guide specifically for the 220/200 kdx to which i set mine to.. (not much different than standard anyway)..will go down on my oil ratio first & hopefully that may just do the trick else i could refit the airbox lid or just go up on the pilot..have noticed a small weep from the front exhaust pipe so perhaps i should replace the O rings along with a little hi temp sealer as that may be contributeing to the bog?
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Julien D
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Post by Julien D »

define "bog". The word can be quite misleading. What most people consider "bog" could be caused by lean condition OR by being overly rich. What exactly is it the bike does/does not do?

but on over run e.g throttle off going down a climb
That bit don't make sense to me. Throttle off going down? Pull in the clutch on the downhills, it's a 2t.
cornishwrecker220
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Post by cornishwrecker220 »

bog...slight hesitation before pick up when opening the throttle..a little similar to when you crack the throttle wide open but not as severe..motor sounds slightly starved of fuel.

over run.. whilst going down a hill in 1st or 2nd gear` coasting` down a climb with the throttle shut but clutch NOT pulled in & engine still in gear..i ride tight rutted trails mostly so with the clutch in its not that appropriate at speed. :shock:
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scheckaet
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Post by scheckaet »

could be a plugged up jet...
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Julien D
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Post by Julien D »

whilst going down a hill in 1st or 2nd gear` coasting` down a climb with the throttle shut but clutch NOT pulled in & engine still in gear


That's really hard on a 2t. You don't want the engine turning high revs with the throttle closed. Piston moving fast, no lubrication, bad idea.

The bog does sound like a lean bog. This doesn't add up with stock jetting though. Have you checked compression?
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