Cut/Paste from Wikipedia:
Choke - When the engine is cold, fuel vaporizes less readily and tends to condense on the walls of the intake manifold, starving the cylinders of fuel and making the engine difficult to start; thus, a richer mixture (more fuel to air) is required to start and run the engine until it warms up. A richer mixture is also easier to ignite.

While I understand that you are experiencing something out of the norm you need to look at the big picture. The choke is used to help warm up an engine. If you push it back in immediately you're not allowing it to do it's job. The goal is to get to a normal operation temperature quickly not quietly... but going from zero warmup time to a smooth idle to 2 minutes is quite a change. It's also probably not as cold in the mornings now either.

I'd give it a $1.98 tuneup and/or a full carb clean just for grins. You may also just have a tank of bad gas.

 

One other thing to check is your idle. I think 1350 is normal.

 

i fill up gas every single day, so it's probably not the gas...91 octane and i don't pump at stations with shared single pump for all octanes...i'm pretty **** about taking care of things....i go to a gas station that has separate pumps for 87, 89 and 91 octane......ultra ****....

when starting and if i push the choke back in too soon, it idles at about 1,100 to 1,200...it'll bog down to 1,000 and cut out...once warmed...it idles strong and fine at 1,300+ range...

when i was using the pricey redline 10w/30 and 10w/40 full-synthetic oil mix, i didn't have any problems with keeping the choke out...this problem only started after i started using yamalube 10w/40 semi-synthetic oil....maybe it's just the oil and the yamalube takes longer to warm....that is the only change i made on the klx250...going from full-synthetic to semi-synthetic oil...

 

(The YammerLube may use more paraffin in their base. Not a "bad" thing; there ARE benefits to using a semi-syn, but I don't want to ignite that oil thread Jihad...)

(The "condensation" theory^ seems backwards; you would experience a shorter warm-up time as the ambient temperatures warm. Your warm-up time has increased....which is what Lotrat is also saying^. We're on the same page.)

My 2 cents.

 

Switch back and see what happens. You can confirm or eliminate the known variable from the equation.

 

seems like a costly experiment especially if i'll be draining the oil again for the valve check/adjustment....i'll just wait to see what happens after the valve check/adjustment....and, than try different oils to see if the oil is the cause of needing the choke out longer than before...

which brand, oil and weight do you use? how long do you have to keep the choke out before you can push it back in after starting?

 

I can just about guarantee this has nothing to do with your oil. My best guess is a fuel delivery problem, but diagnosing carb and fuel problems on the internet is tough...even for a genius like dan888.

 

Ha ha...call him out!

 

Here is an ultra-low-cost test, put 87 Octane-rated gas in it, see if it makes a positive difference. Since you don't have a turbocharger or a higher compression piston/gasket setup, there is no apparent reason to use higher than 87 Octane anyway. You just may fix your problem AND spend less money from here on out.

Octane ratings are NOT Quality ratings......many 87 Octane fuels are superior to many 91 (or higher) Octane fuels, because of the additives that are used to achieve the higher Octane characteristic.

 

might give it a try...easy enough test...