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KLX with TM-36 flatslide pumper carb - idle issues

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Hey guys ive been having a varying idle with the bike, I thought it had a air leak but sprayed with starter fluid around the carbneck and no change in idle. What I did notice was that it rises idle about 500rpm once it warms up from 1400 to about 1900 I think thats normal. But whats not normal is that without touching the idle screw with the bike warmed up the rpms vary almost 1k can go up to 2100 down to 1300.

I had a look around and i noticed that the idle screw moves around a bit, as in it moves in a circular motion not being tighty seated. With the bike on i can adjust the idle fine then i give it a couple of revs and it changes. So I go down to idle screw and give it a slight move (not screwing or unscrewing) with the bike on and my idle changes dramaticly, it changes so easy that the vibration of the bike is definently moving this around.

Ive never had a problem like this so what should i be looking for, are the carb threads to loose or is the screw itself stuffed?
I noticed there is a spring there holding it in place can i put a stronger spring to hold it?
Anything super complicated and unexpected if i remove or does it just unscrew?

Sorry for silly questions this flatslide carb looks like a spaceship compared to smaller carbs ive worked on.
At the moment to have the bike running nicely i have a wire holding it with slight tension and adjusted it from there but its dodgey as lol

Bike is a KLX300R with 351 kit and tm36-68a carb

Thanks for the help!


Edited by George Georgakopoulos

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It's not the screw moving that is the issue, it is the slide moving within the carb bore, allowing air to leak past.

You can test this by greasing the slide to increase sealing inside the bore, but it 's obviously a temporary (and bad) fix.

This happens after hundreds of hours of use.


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It makes sense now i didn't think of that, I have used it many hours and bought used. The wire trick is working for now will give it a test next time carb is off. Will have to replace slide or carb eventually.

If i set idle to 1400 (stock) when warm it will either idle 1400 or rev to 2000 or stall and not start so i have it at 1900 and no issues. I wonder if the slide is a bit loose moving about at low rpm causing unstable idle but higher idle keeps it a bit tighter from the vacuum. At 1900 it doesn't rev to 2400 for example or try to stall. 

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