Just went to up to a 132 main from a 128 and adjusted the clip position on the needle to the 4th slot from the top. (was set as per DJ instructions previously, on 3rd slot). This has noticeably improved the acceleration and overall "power" of the bike. The sad thing is I now have an idle issue. I checked my pilot jet when the carb was apart, and was sure to reinstall it correctly. The float was operating smoothly and the carb was clean on appearance. I started my air/fuel mix screw at 3 turns, but this seemed too rich. I gradually screwed it in all the way, and the engine didn't die. :/ This would have killed the engine before I upgraded my jets. Am I focusing on the wrong issue here? The bike will only stay lit when the throttle is held on, or if the idle is set very high. The bike has a #38 pilot and again I will mention it had no idle issues before. It seems like the pilot circuit is too rich?

Very confused over here

 

Throw the clip back into the 3rd slot. 4th is too rich IMO, keep the 132 though, see what happens.

 

You're basically at sea level, correct? I may have missed it, but is anyone with a stock bore running the DJ needle at that position? Even at sea level that sounds pretty rich. You mention the float seems to operating correctly. Have you checked the fuel level using the clear tube method?

 

At your elevation you"ll still be a little lean with that set up - according to my dyno testing. It is a SWEET power increase - a little over 1hp - over the standard #128/3rd notch stage 2 ( with lid off and a slip-on.) and the increase is mainly all in the upper RPM range where you feel it most.

The air screw setting should be at standard stage 2 ( Is that 3 turns ? ) and the pilot jet should be stock.
With those settings and setup, it'll start instantly, purr at idle, and run like a scalded ape. Perhaps better up top than my MCM'd bike. At least 20hp, 15lb ft TRQ and a great over-rev.
The needle clip and #132 have nothing to do with idle or idle circuitry. Since the symptoms occurred only after you "wrenched" on the carb, I'm afraid you'll have to track down what went wrong during that session. The fact that now the air screw, all in, won't kill the engine is your starting point.


BTW, you should perform the Marcelino Cam Mod (MCM) for another boost in the TRQ curve.

 

Sounds like you might have an air leak

 

At the bottom of our message, you list "YOST Fuel/Air mix screw". Did you have the engine running well at any time with this screw? Is the tip of the screw damaged?

The fuel/air screw circuit is in parallel with the pilot jet. If the engine doesn't die with the screw turned in all the way, the carb is getting enough fuel to run from somewhere. The screw may not actually be closing off the fuel flow or the pilot jet is too big. Or, the carb is trying to run on the needle jet circuit. This can happen if the butterfly is opened too much as the idle fuel is drawn out from very fine holes below the butterfly.

Ride on
Brewster

 

Another observation - Assuming your carb issue is un-metered fuel entry into the intake tract, your fuel curve could be altered(made richer) throughout the RPM range. If so then you may be feeling a added benefit of an AFR that is closer to perfect for max power than the #132/4th notch can offer. #132/4th notch on my bike - as set up like yours -save the MCM, still peaks up to 14.5:1 AFR. We need to dyno test a #134/3rd notch setup, near sea level, on a forum modded stock bore..

Note: My efforts are on a brand new KLX250s - totally unmolested by previous owners. So this is the baseline I modded and dyno tested from.

 

The bike was running just fine with the yost fuel screw. no change in operation after installing that, just more precise control and easier to access.

The throttle is very happy from anywhere past about 1/4 turn. Bike pulls hard. When I let it off and then snap it WOT there is a slight bog and then it goes like an ape. Pilot jet, how did I go wrong?

I too am su****ious that I did something wrong after reinstalling the carb. I was gunna pull the air filter to see if that effects it... I have been mildly su****ious of it being over oiled. If that doesnt change things then I guess its time to start the the stopwatch again and pull out that terribly placed carb for the 13th time :/ I've done this soo many times with no negative effects... Guess I just got sloppy?

Oh yea and I have checked for air leaks multiple times as well with no indication of such.




thanks

 

If it's running good at mid and upper rpms, the filter isn't the problem.

A couple of KLXers have reassembled their carbs and missed putting the needle jet back in (not the needle). Something else to check.

Ride on
Brewster

 

Yes, the 4th notch will introduce a "hiccup" sometimes on a snap to WOT.. But it isn't bothersome especially since there is so much more power to enjoy - raped ape power!