KX85 Stalling & Won't Idle

Hi guys I have a 2004 KX 85 that runs fine, it just won't idle and stalls out when I try to let it idle. When I try to adjust the idle screw, nothing happens. YES I'm sure I'm adjusting the right screw (not the air screw which is set at the manual's recommendation, 1 3/8 turns out). I cleaned the carb, and the problem remained. Took the carb out again and now I see that when I adjust the idle, it doesn't move the slide at all. The throttle, however, works perfectly fine like it always has. Any ideas? Thanks

sounds like you have a dirty pilot jet

I checked the pilot and main jets, both are completely clear and cleaned with carb cleaner. Good thought though!

Should the pilot jet be screwed all the way in? I just read a post saying that the pilot jet should be out about 1 1/2 turns...

Turn the idle screw in all the way in till it gets good firm(mind you don't break it) and you should be able to see it move the slide slightly. If it doesn't it may be worn.  If you get no movement out of the slide pull the throttle stop screw out and see if it has any unwanted wear on it. I'm almost certain it's something to do with this screw as it SHOULD be moving the slide to some degree and with out that theirs not much you can do to get a proper idle. Figure that out first then move on to the pilot jet sizing.

 

Next line of business is if your pilot jet is the right size, follow this to determine if the pilot jet appropriately sized. Take your bike for a short ride letting the engine come up to normal operating temperature. With the engine stopped, transmission in neutral and the bike on its stand turn the air screw clockwise until it just seats, gentle now it’s delicate and you don’t need to torque it down just gently seat it. Now turn the air screw a quarter of a turn out so the engine will fire and start it.  Slowly turn the air screw counter clockwise ( out ) until the point where the engine just reaches the maximum obtainable rpm and continuing to turn the air screw beyond this point wont increase the engine speed (rpms) any further. I find it’s easier to hear the rpm increasing if you set the idle at its lowest possible position without the engine stalling. You’ll want to repeat this procedure a couple times until you’re confident that you’ve found the right spot and that the result is reproducible. When you’re comfortable count the number of turns ( 360° revolutions ) you’ve backed the air screw out to reach this point. The normal operating range is between 1 and 1.5 turns out so if you find the ideal setting is less that 0.75 turns out consider installing the next richer pilot jet (larger number ). If you find the ideal setting is more than 2 turns out consider installing the next leaner pilot jet ( smaller number ).

 

 

 

 

Also going to suggest the next time you need help don't make a new thread about the same topic, it makes things harder for us to follow on here and may cause people to repeat stuff that has been said already.

Thanks moose! By "throttle stop screw" you mean the idle screw, right? And as far as the jetting goes, its a 45 pilot which comes stock. As i understand, when you get an aftermarket exhaust (which i have.. a full pc) you're supposed to rejet it. I dont know what exactly that means, but I would imagine it includes doing what you suggested: see how many turns out the air screw needs to be. But I'll give it a shot and let you know how it goes. 

Thanks moose! By "throttle stop screw" you mean the idle screw, right? And as far as the jetting goes, its a 45 pilot which comes stock. As i understand, when you get an aftermarket exhaust (which i have.. a full pc) you're supposed to rejet it. I dont know what exactly that means, but I would imagine it includes doing what you suggested: see how many turns out the air screw needs to be. But I'll give it a shot and let you know how it goes. 

Yes the idle screw try turning that all the way in to see if you can get it to influence the slide at all please, and report with the findings

Not being sarcastic but why the big concern about the engine idling? If it's idling someone is not having fun! :ride:

Not being sarcastic but why the big concern about the engine idling? If it's idling someone is not having fun! :ride:

 

Well I'm trying to get it sell-worthy. hahaha

 

Yes the idle screw try turning that all the way in to see if you can get it to influence the slide at all please, and report with the findings

 

Okay, with the screw almost ALL the way in, it affected it some. I decided to take the air filter off and clean it, and that helped a little, but it's still not where i want it to be. Still a little too low for it to actually idle.

Sounds like crank bearing is loose or main seal is failing. If you get real white smoke that is what it is more than likely.

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