sup yall im new up here too just joined last week. Pretty cool. Anyway my questionis i just recently had to buy a new carb for my bike. Came in last week put it on the other day. problem is it idles high. the screw on the carb at the throttle is unscrewed to where it aint touchin nothin and the cable on the handle bar is all the way down to decrease idle. Is ther sumthin im missin or not doin right? After awhile if ya pull the thumb throttle back with your finger it ll make it idle down. JUst need sum help. thanks

 

How many RPMs is it running at idle?

 

bout 2500. enough that when ya go to shift the gears that it puts pressure on it. its just higher than it was when i had old one on.

 

you probably have mud/dirt where the cable connects to the carb, thus not letting the butterfly valve close all the way

 

<div class="FTQUOTE"><begin quote>Originally posted by: bmfpolaris700

bout 2500. enough that when ya go to shift the gears that it puts pressure on it. its just higher than it was when i had old one on.</end quote></div>


2500 AT IDLE my scrambler is a two stroke and only idles at 1200!

 

i know thats what im sayin it usually sits thare and counts em down at like 900 rpm. just tryin too figure out how to get it back down again.

 

cool ill blow it out real good and try again thanks man.

 

Here is a note from an old buddy of mine that used to be a wrench in a power sports store. This was actaully in responce to a snowmobile question that I had for him, but there maybe something in here that you can use...

Mikuni carbs are a wonderful and truly adjustable unit. I do not know if the
jetting has been tampered with or not (again a book will tell you at least
the stock jet sizes). The small screw (at an angle) is for pilot jet air
adjustment. Clockwise will enrich (I believe, I've seen many, but have put
these out of my mind in favor of my personal choice of equiptment...they
have a prop and run in water...) You should'nt hurt anything if this gets
out of whack, but startability and idle may be sacrificed. Most run anywhere
from 1 to 3 turns out. Set slightly rich and check throttle response. I
think there is a spring under this screw too. Don't loose it. The larger
screw is the actual idle adjustment It has a fat taper on it if you take it
out to see, and it forces the slide up or lets it down depending which way
it's turned. Turn clockwise to increase idle speed..... However, the jam nut
on top of carb body and the threaded sleeve should be loosened, turn the
sleeve into the cable housing to allow the throttle cable to have some slack
and thus lower the slide in the carb and resultingly lower your idle speed.
In theory, if there is enough thread on the jam nutted barrel, you can set
the idle just by turning that threaded barrel out to the specified speed and
then locking jam nut. Before doing this, back the large idle speed screw
way, way out (so it is ineffective). After idle speed is set, screw in the
large idle speed screw until it just ever so slightly contacts the slide.
Don't let it push it up or idle will increase beyond your already set spec.
Take breather off and put your finger lightly to slide and when you feel it
move up when turning screw, back it off a tad and that's all there is to it.
Reinstall breather and set pilot jet screw and that's it. Do it once and
you'll get the hang of it. Some of the machines have a fail-safe switch
installed in case the throttle cable freezes. They require the idle be set
with a slight amount of tension pulling the cable back (to ensure cable is
free and will close the throttle and slide). If no tension they kill the
spark. Dunno if that machine is so equipped. Keep you spark checker handy to
see if so.

Wrench