New KLX 250 owner as of July09. Have had starting issue since day one. Just got it back from the dealer where they told me Kaw suggested adjusting the compression (lowering ?) to help it start easier. So far, with not much trial, so good. Still have to choke it and understandable, 40's and 50's here in South Dakota. But has not sat for 1-2 weeks. (mine is similar to Deej's, seems to be a time thing)

Questions:

From what I have read (I'm on info overload searching and trying to learn on all these forums) The jetting must not improve starting problems? If what the dealer did doesn't improve my starting I am going to try TNC's drilling of the starter jet.

Has anyone tried or investigated a different battery? I don't even know what stock is, but a motorhead buddy of mine suggested a gel-type battery to try to spin it faster to aid in starting. It seems like mine spins fast enough, its just that after a couple minutes of cranking, my battery is ready to die. So then it's up to the Deej method, or shaken baby method in combo of hooked to a charger.

My 1st performance mod is on order 13T Moose and 45T Renthal and 114 link chain. No problem mixing the sprocket brands is there? Hope this makes 1st gear feel like 1st, and not like I jumped to 2nd.

Considering jet kit. Leaning toward the 300. Want to talk to Dynojet on that. Can I get the Kouba screw from Dynojet too?

When you rejet, what should absolutely be done? Air box mods confuse me. Is removing the lid enough, or do you also need the 200 snorkel? Which filter, UNI or K&N? Without the lid, do you have to clean the air filter more often? Any pics detailing smog removal / air box mods? Haven't really searched these yet.

What's the deal with the headers and slip-ons? Looks, weight or performance? If I did do anything I think I would just do a Q4. Will the jet and airbox mods still be noticeable staying stock exhaust.

Are there any mods that are specific to the earlier models that should not be done to the 09?

Sorry for all the ?'s Here's a pic of my homemade hauler.

 

I, like many others have had a cold statring problem. Mine was solved when I rejetted. Runs like a top. You may try turning the gas off and running it out of gas when you park it. That helped mine before I rejetted. I got my kouba screw from Carls cycle sales. You can try the mod in my sinature and I think you will be happy with the performance. I did mine at 200 miles and didn't wait like others have. You will get many different opinions on what or which way to rejet. I just felt like the way I went was the best. I like the carrier!!!! Good luck

 

In my opinion re-jetting these bike does help in the starting. Since I've done mine I only have to keep the choke on for about 20 seconds. And I've got the same, if not colder, temps where I am. Alot less choke then when it was stock.
As for the battery, if it turns your engine over at a decent rate then don't bother spending money on a different one.
The mods I've done made a big difference in the performance of my bike. IMO if you do all of them you'll notice a difference.
I never drain my carb at the end of my rides and it starts fine every time.
Have fun.

 

I put in an FMF KLX300R jet kit when I installed the FMF Q4/powerbomb exhaust. I've never had a starting problem, but it used to take this bike Forever to warm up enough to take it off choke. Now when I start it, I can turn off the choke almost immediately. I am running a Twin Air filter (with filter skin). I was running it without the airbox lid, but the intake honk was obnoxious, so I've gone back to the factory airbox lid, with no snorkle, and I drilled a series of about 16 1/2" dia. holes. Sounds way better now. Actually it sounded pretty cool before, but my personal tolerance for bike noise was exceeded whenever I opened the throttle more than half way.

Man, I would say if you do nothing else, at least put on a KLX300 jet kit. It's a cheap and easy thing to try, and just might help. You don't have to buy a pipe or mod the airbox when to do a jet kit.

 

+1 what Heavy said. If you don't want or can't do all the mods right away then do the jet kit first.

 

Well first of all welcome to the forums. Jetting will help the bike warm up faster but for most of us it didn't help get the bike started if it sat for a few days. Try this and report back.
First of all lets start (pun intended) with a clean slate. Turn off the gas and take an Allen wrench and drain the carb bowl. After the gas is drained, then open up the valve, wait 10 seconds and pull the choke and it will start. Not maybe but it WILL start.

After that you ask well how can I prevent this from happening every time? Simple. If you ride everyday, you will not have to do this simple procedure. But if you plan on leaving the bike for a few days or weeks or the winter, then this is the procedure.

Shut down procedure.

1. After riding as you are pulling into your driveway, or to speed things up you can do this a block from your house, turn off the gas.
2. Let the bike run until it actually dies from gas starvation, (this may take 2-5 minutes) But that's ok it will give you time to put away your gear.
3. Park it and now you're ready for the next time you ride whether that be in a day, or a month.

Start up procedure.

1. Turn on the gas
2. Wait for 10 seconds
3. Start the bike as you always do

 

When I picked my bike up I could not get it to start. The mechanic said for me to NOT try and start it like my KTM. He said turn the gas on, pull the choke out and press the start button. He said do NOT touch the throttle at any time. Since he showed me that trick I have not had a problem. The bike starts every time. I have since put the FMF Q4 slip on and have ordered the Dynojet kit for it. Great little toy bike to goof off on.

 

that sure does not help me. i rejetted and it runs good but always hard to start if i stall it after being run, not dumping it either, not real quick to start cold either. i usuall throw it in 4th or 5th gear either push it or go down a hill if available, NOT GOOD!!!

 

Rejetted??
Most people are still under jetting this bike. It likes fuel (yum yum.) Stock bikes in AUS and NZ get a #132 mian jet. This should be a starting point for most unless you live above 5000 feet.

What jets do you have?
Do you have an after market filter? (makes a big difference.)