Hello I was wondering if anyone would be able to help me with a problem I'm having with my 09 klx 250 shutting off at idle.

This spring I cleaned my carb, removed the airbox lid, installed a dynojet kit, and added an fmf powercore slip on muffler. After installing these mods I rode it for about 45 minutes and it ran perfect. Alot better throttle response and more power! However, the next day when i rode it and would come to a stop it would return to idle for several second then while it's idling it sputters and shuts off. It starts right back up and then would run fine while i was on the throttle. It doesn't do this at every stop and the weird thing is that it seems to do this more often when the engine is warm. It idles fine while warming up and won't shut off at stops on short 5 minute rides.

Thanks in advance for any suggestions.

 

You have openned it up to breathe better by doing airbox mods and putting on a slip-on... and in doing this you have altered the air/fuel mixture. Now, by putting in the dynojet main jet and fuel needle you have returned that balance when the throttle is open, but you have not addressed it at idle (when the throttle is fully closed) which is why you're having this problem. It will be even more pronounced when the bike is warm/hot as the fuel evaporates quicker, and so makes the a/f mixture even more lean.

To fix this, you may be lucky enough to just need to adjust your air/fuel screw. It should be about 2.5 turns out when you have the right pilot jet installed. Try turning it out (counter clockwise) another half turn and see if that fixes your problem. If you need to turn it out any more than that (so a total of 3 turns out from fully seated) then you need to go up a size on your pilot jet.

As a rule, at sea level you should be looking at a #38 pilot jet with the mods you have done, and the a/f screw starting at 2.5 turns out. Ask your dealer for part number 92064-1119 (Lowest price guarantee on parts / accessories for Kawasaki Motorcycle, Dirt Bike, ATV, Jet Ski - OEM parts for less) and install that - it should solve your problem.

 

Thanks arctra!

That makes sense. I'm a little above sea level and have tried adjusting the a/f mixture screw anywhere between 2 and 3.5 turns and the position it's at now is where it runs the best so I think i'll need to replace the pilot jet. I'll order one from my shop monday and let you know how it goes.

Thanks a lot for your advice. I didn't even think of that!

 

Any chance your idle speed is set to low, that can be adjusted by a simple screw adjustment on the carb also. And with the rejet it could affect the idle speed as mentioned above.

 

Sure is easy to try.

I have a sorta-similar setup that idled fine with a 35 Pilot, but, would pop too much on decel, even with the a/f screw backed out as far as I dared. Popped in a 40 Pilot and that's fixed, but, it never affected the idle enough to notice. So, I'm thinking just bumping up the Pilot isn't going to fix it...unless the current pilot is clogged somewhat.

Regardless, like Arctra said, you've significantly leaned out the mixture with your modifications, and need to address that to make it run just right.

 

I'm familiar with jetting on other bikes, and agree that the pilot needs to be increased. It seems DynoJet just leaves out the pilot jets. Does anyone know why? Increasing the pilot is night and day difference for starting and low end torque.

These guys are great, but $13 is steep for one jet. Do dealers carry the pilot jets? I'll try a 38 & a 40 and report the results.

http://jetsrus.com/a_jet_kit_dirt/ka...0_KLX250SF.htm

I'll probably just order it, at least Jets R Us is fast and easy.

 

Your dealer should stock the jets. Just phone them and ask if they have this part number in stock - it's the #38 jet: 92064-1119
(Lowest price guarantee on parts / accessories for Kawasaki Motorcycle, Dirt Bike, ATV, Jet Ski - OEM parts for less).

I would be surprised if you needed to go to a #40 pilot, but in saying that, one of the Aussie aftermarket slip-on manufacturers (TK pipes) shipps you a #40 pilot with their muffler for the KLX. When I challenged him on whether it would be too rich, he defended it by saying he had done a lot of testing with his pipe and was sure the #40 was the right one to go with. So I guess it's worth a try.

 

I run the Dynojet kit and the stock pilot and it starts and runs great so I'm not convinced the pilot needs to be changed for a simple stage one or two upgrades.

 

What altitude are you at? If you're high up and still have the stock muffler then you are possibly right.

But with a powercore slip-on and the other mods mentioned, it is pretty much what my bike was before I put the FCR35 on, and in that configuration at sea level my bike would not idle when warm. Was downright dangerous stalling at traffic lights and not being able to get running again quickly and easily!

So from personal experience I AM convinced

 

I'm at sea level to around 1500 ft. and with stage two per the Dynojet instructions, a Powercore4, Powerbomb and a Uni filter. The bike runs perfect at all rpms from idle to wide open and has nearly as much power as any 250cc bike I was ever on, so no in not every situation do you need to mess with the pilot jet. With my experience I'd even advise against it.