Problems adjusting idle on 38mm airstryker

[edz250r]

Hey guys....the only way that I can adjust my idle/rpm is by making adjustments to the thumb throttle screw where the cable slides into. I thought you could change the idle speed by turning the black screw on the side of my 38mm airstryker, but it doesnt do anything to the rpm's.
Does anyone else have this problem or can they turn their screw and make big changes to the idle without touching the thumb throttle adjustment?

[wilkin250r]

Is your quad able to idle? Why do you want to change the idle speed?

I had a problem a while ago in which I couldn't change the idle speed on the carb, only to find that it wasn't a proper idle to begin with, I was way too rich. Once I got the idle jetting dialed in, I was able to adjust my idle speed using the choke/idle screw.

[danbobsR]

Im going to say the same it is probally to rich that is why the screw is doing nothing

[edz250r]

I'm able to get my quad to idle, but only be adjusting the thumb trottle adjustment. The idle screw is useless right now.

Would it be the pilot jet that is too rich? I'm using a 50 now....

[Hoppedrap]

Take the idle screw out and cut about 1/4 off the spring. Had to do it to all my Keihins.

[250R Baja Rider]

Your problem is not the jets.

Your problem is the adjustment on the throttle is too much.
You have to losen that adjustment at the throttle until you see the slide on the carb completely seated on the carb bottom.

Only then the idle screw on the carb will work.

What happened here is that the slide is already liftted beyond the adjustment range of the carb.

Take the carb off the intake boot. If the slide is not completely or almost closed, losen up the cable at the throttle. Once the slide starts to come down or close, you will be able to play with the idle on the carb. Make sure the idle is screw is almost all the way out before you losen the cable at the throttle.

:D

[edz250r]

Thanks, Baja. Does the idle screw work by lifting up the slide when you screw it in?
I dont HAVE to mess with the slide and idle screw if I can get it to idle fine now by messing with the throttle, right?

[250R Baja Rider]

That is exactly right.

The idle screw will lift the slide as you screw it in making the revs go up. The exact opposite applies when you unscrew it.

At that point, you will need to evaluate if your needle is the correct one cause as you lift the slide, you lift the needle too.

Good luck playing with it. Just remember, it is always better to start with a rich mix than a lean mix.

Lean mixes can lead to engine failures.

[jon370r]

As Hoppedrap stated I also have had to remove the spring from the idle screw to get enough adjustment to idle properly with both my 38 Airstriker an 40.5 PWK. I have also seen a PWK with a broken tab on the top of the slide. This tab is where the idle screw holds the slide up, if its gone the idle screw won't function at all. Another possibility would be the black plastic idle screw itself is warped or broken on the end that contacts the slide, preventing it from raising the slide. Good luck with your trouble shooting.

[beerock]

I adjust my idle with the cable, always have always will.

[wilkin250r]

One point to clarify. Only on Keihin 4-stroke carbs does the idle screw lift the slide. Not on the 2-stroke carbs.

I'll have to take my carb apart again and look at it to figure out exactly how it works, but I know for a fact there is no mechanism for the idle speed screw to lift the slide.

I believe the idle is a separate fuel passage that bypasses the slide completely, but it's obviously much smaller than the slide passage. So if you have that slide open at all, even a tiny bit, it will easily override that small idle air passageway. So if you have your idle set by your throttle adjustment, it will drown out the idle passage, and your idle speed screw will become useless.

I had this same problem once, I couldn't get my quad to idle, so I HAD to use the throttle cable adjustment for idle. Come to find I was way too rich, I was running a 58 when stock was 42. I was running a larger carb, so I switched to a 45 (or maybe 48) and now it idles perfectly, my throttle cable is all the way out (slight amount of slack in the cable, so I know my slide is completely closed), and I can adjust my idle with the idle speed screw, and it actually works!

I have to work on my quad tonight to get ready for Memorial Weekend, if I have a chance I'll take apart my carb and get a better explanation of the idle adjustment, complete with diagrams.

[edz250r]

Thanks for the info, guys.

Wilkins - Keep me posted if you do take apart your carb. I would do it myself, but I hate trying to get the darn stock intake boot from the airbox to fit back on the carb (I have to boil it so the rubber will stretch!)!!

[wilkin250r]

It may not be the 38mm Air Styker carb, even though I have one, I don't feel like taking that one apart, it's set up so nicely right now. But I do have a 36mm Keihin that I have as a backup that I have no problems taking apart, and I imagine the idle is the same on both. It's just sitting in a box, no boots to mess with.

[velocityatv]

ON THE 38 A/S THE IDLE SCREW HAS A TAPERED END THAT PRESSES ON THE BOTTOM LEFT OF THE SLIDE.

MAKE SURE YOU HAVE PLENTY OF PLAY IN YOUR THROTTLE BOX I USE 1/8" TO 1/4" OF PLAY IN THE THUMBLE THROTTLE LEVER AS A REFERANCE. TOO TIGHT CAN CAUSE THE THROTTLE TO STICK, IF THE CABLE ISN'T ROUTED SMOOTHLY ( NO SHARP BENDS )

IF YOU DON'T GET ANYWERE WITH YOUR IDLE SCREW TRY BUMPING UP THE IDLE AIR SCREW ( SMALLER SCREW THAN THE ENGINE IDLE MOUNTED BEHIND THE SLIDE ) IT'S A SMALL BR*** SCREW RIGHT NEXT TO THE AIR BELL WERE THE BOOT ATTACHES.

A GOOD PRESET TO START WITH IS MAKE SURE THE NEEDLE CLIP IS IN THE MIDDLE POSITION, MAKE SURE TO HAVE THE SLIGHTEST BIT OF SLACK IN YOUR THROTTLE BOX, TURN THE IDLE AIR SCREW IN ALL THE WAY ( DON'T CRANK DOWN TOO TIGHT IT'S BR*** FOR GOODNESS SAKES ) THEN TURN IT OUT 1.5 TO 2 FULL TURNS OUT. THEN TUNE FROM THERE.

IT'S ALSO A GOOD REMINDER TO MAKE SURE YOU HAVE A NEW PLUG, CLEAN AIR FILTER, GOOD REEDS AND GOOD GAS WITH A PROPER FUEL/ OIL MIX. ANY COMBINATION OF THESE LITTLE THINGS CAN CAUSE IT TO IDLE A LITTLE ( DOGGY )

HOPE THIS HELPShttp://www.sudco.com/catalog105/106-109.pdf

[wilkin250r]

Are you sure? I don't see any way the idle speed screw (which is the same as the choke) can hit the slide at all.

I'll have to take apart my carb and look at it more closely.

[Dave83]

On the a/s carb,the choke and the idle stop are seperate.I believe the idle screw is a stop for the slide.The post about the cable keeping the slide too high would make the most sense if this is true.

[wilkin250r]

Originally posted by Dave83
On the a/s carb,the choke and the idle stop are seperate.

Well son-of-a-&*$^#, are you sure?

The choke and idle are the same screw on the PJ carbs, and there is no mechanism for the idle screw to lift the slide.

Damn, I hate being wrong. Now I HAVE to go disassemble my carb just to verify.

[jon370r]

PWK carbs don't have the same idle adjustment as the PJ style stock carbs. The choke Knob is the same and it turn but that doesn't control the idle on the PWK. There is a large flat head screw that adjust the height of the carb slide for idle.

[wilkin250r]

Okay, I was wrong. :ermm:

Everybody get their shots in while you can, cause it ain't gonna happen again. :blah:

[Dave83]

Dont let it happen again,Wilkin.:D

[beerock]

the idle holds the slide up thats why i use the cable, same difference. I know you rsuppose to have 1/8 to 1/4 " of play in the throttle but its much easier for me to adjust idle at the throttle then by the carb, just the way i like to do it. Ive never had a stuck throttle.

[edz250r]

Wilkin - You can blame me since my post started this whole mess! LOL I did get my answer though and I thank all of you!!

[JTRtrx250r]

ED, be sure to set your slide flush w/ the venturi of the carb at WOT, most people dont do it and wonder why jetting varies so much and can be such a PITA for some, otherwise your "fully "true" to the jetting, if you dont... it pulls the slide up too far whichs effects turbulance, and alters jetting. If the slide pulls up too high it pulls the needle out farther which really isnt what you think your jetting is. Im real picky about my carbs and like to know exactly where I am w/ it... not what I think it might be;)

[edz250r]

Thanks, JTR!

I cut about 1/2 of my idle screw spring off and loosened the throttle cable before screwing the idle screw back in and the idle screw now works like a charm!! Thanks guys for helping me out on this one!