97 kx carb questions

[kawraper]

I looked through the carb stickey and couldnt find the info im looking for.

What are the electronics on my 97 kx125 carb? And what is that post that looks like a squirter in front of the slide?

Im having issues of plug fouling. It only happens when I first start it, let it idle for a minute then when I go to take off it fouls the plug right away. If I fire it up and immediatly take off and gas it good clear out the cylinder its fine. But when I let it idle for a minute it wants to foul on take off.

Once its going the plug doesnt foul and it runs like a raped ape. Im unfamiliar with what this electronic stuff is. I just want to be sure it isnt the root of the problem before I start messin with the needle setting.

Thanks.

 

[_JOE_]

Sounds like the pilot circuit is too rich. Where do you have the air screw set?

 

[kawraper]

I dont know. Just bought the bike last week. I opened it up and cleaned it out. Havent really messed with it much other than that.

Was thrown off by the fact there is electronics hooked to a carburetor????

 

[_JOE_]

Alot of bikes have throttle position sensors. Some have electronic "power jets". As far as I know these rarely need messed with. The TPS on my rm had an arm of sorts that rode on the slide, you had be pretty cuatious when putting it together that this was together properly.

 

[kawraper]

Ok kewl. Just wanted to be sure that it wouldnt have a major effect on anything.

 

[Kawi4life]

Sounds like the pilot circuit is too rich. Where do you have the air screw set?

+1. Get a couple smaller size pilot jets (they're cheap) and you can also turn the air screw out just a 'tad' and drop the needle down one notch also. Every KX I've ever owned come from the factory too rich on the bottom, at least for my weather and elevation. If it's really that bad I would drop two sizes leaner on the pilot and don't touch anything else for a starters and see how it runs.

You'll know if you go too lean on the pilot the bike will blurp and cut out off the line when stabbing the throttle and if you go too lean on the air screw it will surge and be much harder to start. It's really simple actually, the first time I tried to jet a bike (actually a Quadracer 250) I got it spot on my first time doing it just by making a mental note how it ran at various RPM's and knowing what range each jet controls.

 

[kawraper]

Ok so heres the deal. If I start it and hop on it right away and ride it real easy to warm it up its fine. If I start it and let it idle for any amount of time when I go to take off it fouls the plug right away.

Just wanted to see if that is also consistent with the pilot.

Thanks for the help guys!

 

[_JOE_]

The pilot provides the fuel to allow the engine to idle. Once the slide begins to open the fuel starts to flow through the main jet and is restricted by the needle until the slide gets up to the top. Find the airscrew and count how many turns it takes to get it to seat (turn clockwise).

 

[Killdrums]

1 1/2 to 2 turns out on pilot/air screw...anything more than 2 turns get a diff jet