This is my first post but I've been lurking for a few weeks.

I bought a CRF230L a few weeks ago and hated it. Fortunately I was able to sell it quickly and found a really nice 2012 KLX250s with 4800 miles on it. I have four boys ages 13, 11, 7, and 4. The oldest 3 trail ride with me and I do some country roads with my wife.

After lurking around here I did do some minor modifications. I have removed the snorkel and put in the Dynojet stage 2 jets and spring. I also followed their instructions for the fuel screw. I like it relatively quite so a slip on is not in the plans at the moment.

Prior to the jet change this bike fired up very quickly when cold or hot. Now, it is difficult to start when cold, enough that I'm considering putting the old jets back in. Has anyone else experienced this?

 

The only thing I've heard that helps with starting on a stock KLX250s is to drill out the pilot(?) jet.

If you're going to go through the trouble though, I'd just do the MCM mod. Disabling the KACR resolved ALL my cold and hot start problems. It's not a horribly difficult mod, and it really wakes the bike up without removing stock parts. It'll actually quiet down the intake noise as well.

 

Your results aren't typical.
Where was the fuel screw when you started and where when finished (e.g., 1 1/4 out from seated at first, 2 turns out final position)? This pilot fuel screw position can impact starting with 'out' being more rich and generally easier starting.

Turn the idle screw in a little also (faster idle) and see if that helps.

You say "putting the old jets" back in. How many jets did you change? I thought the DJ kit included main jets only, so only one to change. And the main jet should have zero influence at closed throttle.

Did the rubber diaphragm go in properly?

 

Most likely the idle mixture screw, but in case it's not...

Make sure the diaphragm, needle, needle housing, spring are all assembled correctly and are in good shape.

My manual actually showed the needle going in through the top of the spring holder/housing with the washer being on the top side of the housing with the needle sticking through bottom. This won't work and won't keep needle secure and would screw up starting. Needle and washer need to fit snug underneath the white housing/hat that holds spring.

 

I've worked on a bunch of carburetors lately. Sorry about the confusion. The dynojet kit only includes the main jet and that is what I changed. I don't remember where the mixture screw was initially but its at 3 complete turns out per the instructions . I will try turning the mixture screw in a little.

I reassembled per the diagram on dynojet's website and attached. Is that correct?

 

That little white basket needs to be oriented correctly. IIRC there's a hole under the basket which can't be blocked.

 

Forgive me please, in advance - but there is really no reason to tapdance around the issue - As you said, your bike started perfectly fine before you removed the carb, worked on it, and reinstalled it. The DJ kit has nothing to do with it. Main jets, springs, and needles have nothing to do with cold starting. The problem was created during the "wrenching session" and you'll have to keep at it until you find and fix it. Sorry.

How bout the float system? Was it handled it in a way that could have borked it?
Any chance the fuel screw got screwed in all the way and over-torqued - damaging the screw and/or its' seat?
What about dirt/fuel contaminates/improper cleaning of parts etc etc that resulted in debris getting inside an orfice or passageway?
Did you remove and inspect the pilot jet and needle jet? Check them carefully to make sure the myriad tiny holes are clean and unclogged.

 

Thanks for the advice. I turned the fuel screw to 2 turns and it fired up pretty quickly when cold. I'll try it again tomorrow after it has sat all night. If that not the culprit, I'll disassemble the carb again. I was pretty careful with the floats and didn't over torque the fuel screw.

The motorcycle runs great once it starts when cold or hot.