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Discussion Starter · #1 ·
i just did the cam mod, and i checkd my jetting while carb was out. here's the info. i just bought this thing. it's an 04 with the folowing mods: cam mod, full sparks pipe big bore, airbox kit also. when i picked it up it fired right up but had a small stumble when giving it gas. his set up was lid on, pro design filter, and sparks pipe. it has a 168 main, my prob is the small one. im having seeing what it is. i thought it said 90, but after researching on here, i know that aint possible. going back to the garage to look again. also i bought a billet fuel screw.just twist out the plastic one and replace with the alum one? im new to these carbs. last thing i jetted was a 99yz 250 2 stroke. then have beenplaying with fuel inj since then. please help. also the quad sat for over a year. the gas was way old. it's drained now also.
 

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Discussion Starter · #2 ·
ok i just checked again it has a 45 pilot it was partialy blocked. i sprayed it with some carb cleaner and have all the jets in a cup of cleaner right now. would that have made it stumble? also dummy me unscrewed the small brass srew with the spring on it. i reseated it and backed it out 2 turns. looking at the bottom of the carb here's what i got :small screw with spring on it, the pilot(45), main 168, and this other jet that looks to have 90 on it. how can i tell what needle is in it?
 

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Discussion Starter · #3 ·
QUOTE (demented_22 @ Feb 17 2009, 02:36 PM) index.php?act=findpost&pid=747453
ok i just checked again it has a 45 pilot it was partialy blocked. i sprayed it with some carb cleaner and have all the jets in a cup of cleaner right now. would that have made it stumble? also dummy me unscrewed the small brass srew with the spring on it. i reseated it and backed it out 2 turns. looking at the bottom of the carb here's what i got :small screw with spring on it, the pilot(45), main 168, and this other jet that looks to have 90 on it. how can i tell what needle is in it?[/b]
also what can i use to slide thru the pilot to clean it out
 

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to take the needle out u have to take the top of the carb off, there is not a different size of needle just adjustable ones.
 

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Discussion Starter · #6 ·
QUOTE (demented_22 @ Feb 17 2009, 02:48 PM) index.php?act=findpost&pid=747462
thanks back to the garage![/b]
ok it looked like it said ncvo which im assuming its a ncvq( my eyes are bad) outa contacts. the clip was in the third pos. from the top. am i right in thinking the small screw with the spring on the bottom is the one i replace with the long billet one i bought?
 

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search for "bog"

the yfz's have a common stumble when you punch the throttle, best fix is to replace the leak jet with a number 35 (its in the bottom of the bowl)

and do the zip tie mod on the acclerator pump linkage (search o-ring or zip tie mod)
 

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Discussion Starter · #8 ·
QUOTE (leveldrummer @ Feb 17 2009, 02:57 PM) index.php?act=findpost&pid=747466
search for "bog"

the yfz's have a common stumble when you punch the throttle, best fix is to replace the leak jet with a number 35 (its in the bottom of the bowl)

and do the zip tie mod on the acclerator pump linkage (search o-ring or zip tie mod)[/b]
cool bud! she is all zipd up. you said the leak jet is in the bowl right? nevermessed with these things. thanks for all the help. btw is that jetting close? 168 45 needle in the 3rd groove?
 

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Sounds about right depending on your altitude and temp. Best way to tune that bike without a dyno is to just ride it.. like i tell everyone else, here's some things to look for:

Slow acceleration 3/4-full throttle = main circuit (main jet, needle clip position)
backfiring or "popping" on decel = pilot circuit, too lean.

People think that popping or backfiring is due to being rich/fat.. I've only experienced a loss in power. If you're to lean, however, that's when you notice a lot of bad noise and flames shooting out the back end of your machine.. not to mention an internal heat problem that could cost you money.
 
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