Just bought my first bike it's a 2010 klx 250s. It takes forever to start even after letting it run out of gas the day before. Once I get it started I have to keep the choke all the way out for atleast 5min or it will stall. From reading forums on here they seem to have a problem starting but I have tried all the ways those people have stated and it still doesn't want to start. It has a FMF exhaust so I'm assuming it needs to be rejetted but is that the cause of the rough starting and choke issue? I just wanna hop on the bike and go not sit around and let it warm up. The air filter isn't dirty and the plugs gapped correctly. If it does need to be rejetted how do I know what size to get?
Thanks

 

Yeah, from owning one/being on this forum, klx250s bikes often are cold blooded.

I'm not much help, but 3 minutes before you finish your ride, turn your petcock off, also, rejet, and maybe drill a larger hole into the choke jet.

I thought the 2010 model has efi. i guess not.

 

Basswacker,
It's pretty common for this bike to have starting difficulties, and it often is worse when cold. Opening up the fuel mix screw to around 2.5 turns out may help. A larger pilot jet (#38 or #40) may help, but then you may have the wrong size for best running (what's your elevation). The FMF isn't the culprit. The best solution is to drill out the starter/enricher/choke jet to 0.018 inches. Do a search for it in the FAQs (see my sig line for a link).

 

Or check theKLX250S Cheap Mods link in my signature. It lists the changes and some other stuff. It is an accumulation of work done by others since the bike came out in 2006. Both my brother and i did the jetting modifications listed and the bikes start near instantly. I also disabled the compression release, which isn't needed on an electric start 250. My bike starts near instantly and will be off choke within around a minute.

 

Thanks for your help so far. My elevation is about 100ft. What's pilot jet do you think would be better for Massachusetts weather?

Reading the KLX FAQs link one of the articles says to drill it to .020" but I have also read .018" are those different because of elevation or people's opinion?

 

Elevation has very little to do with it. You only run this jet with the choke **** pulled so there's no fine tuning to get it to run just right. You just want it to start!

A lot of the low elevation riders go with a larger pilot jet. There's a way to determine if your pilot is the correct size by adjusting the mix screw and finding the best (highest) idle speed. This should be between 1 and 3 turns out. If it's less than one turn, the pilot is too large. If more than 3 turns, pilot jet is too small. Increasing the pilot jet size also helps get more fuel in during startup and that's one reason I believe those with larger pilot jets have fewer starting issues.

There's not much difference between .018 and .020 inches. If you go big, it may be too rich during starting and will start to bog, which isn't a big deal. Just shut off the choke earlier.

 

Hey Bass

I am in Ma. too. My klx has stock snorkel, fmf q4 ,dynojet (at stage one) and a 38 pilot 2 1/4 turns out. Bike starts with ease.

Mine too was very cold blooded stock.

 

If you are going to pull the carb for a tear down, there is a lot to check and clean.. The entire pilot system must be squeaky clean for proper starting - For instance, it sounds to me like you have a few aeration holes clogged on your pilot jet or a partially clogged Pilot Air Jet (PAJ)..

If you ride your bike every day, and the carb is functioning properly, it should cold start very easily. Being a used bike, there is no telling how the carb is set up or what settings are being used..

 

Based on the past "history" from a variety of resources the .020" helps a lot when starting... which it did. The pilot covers the idle mix for the regular operation. The reason for the pin drill by hand is that it is a fragile job much more suitable for being done by hand rather than machine. Pippen's article points out the stock starter is at .017 and he did a .020 as did the rider in another article also listed there.

It isn't hard to learn what has been done once opened up. No one would only drill the starter jet without changing all the other jetting. It would be more likely they wouldn't, even if changing the jets.

I agree on the idle mix screw between 1 and 3. At 900 ft elevation, 2.5 turns with the 38 pilot jet worked well for us. I didn't bother trying anything different from the 2.5 turns since it worked well. Fact is I probably should turn it to idle drop clockwise, then count the turns to idle drop counterclockwise then split the difference, but it worked so well and I still have the stock hard-to-get-to screw.

 

You mentioned the FMF. Are you running lidless, snorkelless, or stock lid setup?

Your prob sounds a lot like how the bike starts when its stock. There are indeed some monkeys out there that want to slap a pipe on a bike with out properly adjusting the air intake setup and jetting.

Best thing you can do is order a Kouba T-handle fuel mix screw, proper pilot and main jets for whatever setup you have (trust me, you dont want to go through the trouble of pulling the carb and NOT having the parts you need ).

Once you have the parts in hand, pull the carb, set it up according to the basic recipes found in this forum, and put it back together. A larger pilot jet and T-handle fuel screw can work miracles for starting and idle warmup time.