i need to know the carb basics. i think my ds is not running right and i want to experiment with some carb adjustments to see if i can get it running right. is there a web-site or links that will explain how to adjust the stock ds carb.

 

Yes...Use the search option on the forum.. You will learn more then you need to know.

 

javex,

Please don't take this the wrong way, but you may want to elaborate on the "running not right", as it may not be the carb, especially if you're talking about working on the '04.

jbt

 

elaboration...

when i go wide open throttle fast after i shift into a higher gear...and my rpm's are lower... i think at about 1/2 throttle my quad just hesitates .. and if i don't let off the throttle and do a slower accleration, i think my quad wouldn't almost choke and stall. to about 1/2 throttle, it is smooth..and after 1/2 throttle it is smooth .. what is causing this? .. this problem really only happens is the scenerio i just described.. if slowly acclerate from a low rpm to high rpm, no problem .. from low rpm to high rpm in 1st and 2nd gear .. no problem .. only if i punch the throttle at low rpm in higher gears does it happen

 

what about any mods to the bike? airbox, jetting, endcap...etc.

jbt

 

i have been searching old posts... but i have not even basic carb knowledge .. i don't know where the screws are to adjust any of the jets .. isn't there like about 3-4 jets .. main, idle, a lower-mid throttle jet? ...... and so on..

 

completely stock...

 

boss,

from what I'm hearing, I would lean toward the air filter popped loose or a vacum line is loose. I would even said the vent tube for the gas tank is kinked. But I wouldn't adjust anything until you checked around under the seat real good with a flash light.

Take the bike for a test drive. loosen the gas cap and see if it runs much better. This will let you know if the vent tube is kinked.

jbt

 

1) idle mixture, controlled by an adjustable screw - this mixture is used at idle only, when slide is fully closed. this mixture can also be responsible for the infamous "popping" after letting off the throttle and coasting at higher speeds. screw is on bottom of carb, in front of bowl up a little tunnel.
2) pilot circuit, controlled and adjusted by changing pilot jets - this circuit supplies fuel from off idle to 1/4 throttle.
3) needle, adjusted by clip position - this device meters fuel flow coming up through the main jet and up the tunnel called the needle jet, which the needle rides up and down in, from 1/4-3/4 throttle.
4) Main jet - controls fuel flow at wide open throttle, after the needle is raised all the way by the slide out of its way. Main jet can also effect needle circuit above, since fuel the needle meters does have to come up through the main first. For this reason, needle adjustment issues are sometimes confused with main jet issues - sometimes a guy can think his needle setting is a little rich or lean do to a stumble at 1/2 throttle when in fact the main is the culprit - sometimes. the main jet is located up inside a brass sleeve, screwed into the bottom of the needle jet.

The stock carb also has a starter jet - looks like a main, in front of the main which is screwed into the needle jet like its supposed to be, but not all cabrs have this particular jet. this jet size can be increased to aid cold weather starting.

Of course there's also the choke circuit - which is not the typical butterfly choke like a lawnmower has - it is just a valve that opens a little fuel port to allow the syphoning of extra gas.


I had the same stumble issues you have when hammering to full throttle from 1/2, under load coming out of a turn or shooting up a hill - I got it smoothed out some with jetting and needle adjustments, but ultimately the best cure was changing to a Dynojet kit - the dynojet needle is longer and tapered differently to offer a smoother and better throttle response. It was the most satisfying mod I ever installed when my motor was still stock. not everybody has this problem, but those that do really appreciate the dynojet needle after trying it.

 

i had this "stumbling" issue before during breakin. over the days, it just went away. then i didn't ride or start my quad for 4 days (friday night i rode) and the problem was there again. today i rode again, and the problem is almost gone. any thoughts on what causes this problem?