Bike will not idle down?

[5.13Rockclimber]

I need some help! Bike has ran top notch for the last year, a couple weeks ago bike started to rev out of control.
Start the bike up, it revs high, get on and ride a round still revs high it will not idle down. Tried adjusting idle screw and air screw no help, they do nothing, except make it rev higher.
So, I but new spark plug in and cleaned airfilter still high rev.
Next messed with jets, changed main and pilot jets up and down from what I had in there. Still high rev. I have no idea what to do next :bang: , PLEASE! offer some suggestions.

I have a RB carb mod, 150 Main and 40 Pilot jet,V-force reeds (the bike ran like top,more power than my stock kx250).
I do not know what other info you KDX gurus might need to help me out, just let me know.

THANKS

 

[foots]

Sounds like an air leak

 

[pete fry]

Ill second an air leak.

 

[glad2ride]

I'll third it.

I was thinking the perhaps colder temprature of fall approaching would do it, but you said you had messed with the air screw and went one larger on the pilot. Well, then again, I am not seeing where you fooled with the needle clip position any. Have you?

 

[5.13Rockclimber]

I did not move the needle clip position any, I do not know the clip postion off hand but should I go up or down?
If it is an air leak, how do I determine if it is and how do I fix it?
Sorry, but still pretty new to dirt bikes, this is the first bike I have ever owned and its only been a couple years.
Thanks again for everyones help!

 

[Green Hornet]

Spray some WD-40 or Carb Cleaner around the Intake Manifold (Boot). See if the rpms change. Also, have you checked the throttle cable???

 

[5.13Rockclimber]

I will try the carb cleaner tomorrow. I was wondering about the throttle cable, when I was changing jets I noticed the throttle slide had a 1/8" to 1/4" opening. It has been over a year since I torn into my carb. Is the slide supposed to be completely closed or is there supposed to be a small gap, I cannot remeber. This might be my problem!

 

[Green Hornet]

When you turn the Idle screw in, it will raise the Slide. Turn it, then back out 1.50 turns & go from there. Does the RPMS increase when you turn the bars??? Have you adjusted the cable???

 

[blackduc98]

I was wondering about the throttle cable, when I was changing jets I noticed the throttle slide had a 1/8" to 1/4" opening. Is the slide supposed to be completely closed or is there supposed to be a small gap, I cannot remeber.

Do you mean that you can see daylight thru the gap under the slide? Unscrew the idle stop screw completely, i.e. remove it from the carb (bike better be squeaky clean before you start this). Then look into the bellmouth of the carb: the slide should be completely closed. If it isn't - that's a problem. Unscrew carb top and disconnect throttle cable from the slide, and then reinsert slide into carb and see if it closes the gap completely. If it does then the problem is your throttle cable. If it still doesn't cover the gap then there could be something jamming the slide. Acording to Eric Gorr's book the slide can stick if dirt passes thru the air filter and gets wedged in the wrong place. Another way to force dirt into the slide is to lube the throttle cable without disconnecting it from the carb first. Also note that slide and slide bore can wear out over time, and the slide can lean to one side (I would use the word "c.o.c.k." but DRN doesn't like that word) and cause a stuck-open throttle condition. Your bike is a 2003 so I would not expect normal wear to be a problem, unless dirt passed thru the air filter.

 

[5.13Rockclimber]

Yahoo :cool: , thanks guys the bike is back to its old self again!!!!
I tried the carb cleaner trick and there was no change. So I checked into the cable issue, sure enough the cable was screwed out near the throttle. Screwed the throttle cable down and the bike runs like a dream. I must have messed with the cable for some reason when putting on new grips.
Thanks to everyone who helped me out, maybe someday I can return the favor to someone else.

 

[mg89]

stuff happens :cool: