Thanks KLXster, your always very helpful. As is everyone else!

If installing the #40 pilot jet, will it still be necessary to remove and cap off the air injection system?

 

Nuthin but love for ya .. but maybe you outta read a little of the link you keep posting on all the decel pop threads:

"Lean Carburetion:

While exhaust system popping may be considered normal, it is certainly made worse by an overly lean idle circuit. (clever use of the word "may")

Be sure that your carburetor's pilot jet is the correct size and that the idle air mixture screw is correctly adjusted before looking for other causes of popping. The procedure for adjusting the pilot circuit is covered in the Tuning Manual."

 

Don, you just need to remove your carb, fully disassemble it, clean the debris out of all the circuits, and correctly reassemble it - do this right one time, and your problem is fixed, do it wrongly or poorly and you'll be removing your carb over and over until you get it right..

Make sure the OEM fuel filter is still in the fuel line - perhaps add an additional filter to the line.

Also realize that some other issues could be causing the onset of decel pops - like a leaky carb boot - or any other vacuum leak.. But usually, such vacuum leaks are pervasive and create lots of other driveability issues..

 

Right on, Thanks y'all. Will check back in once completed.

 

If the bike isn't running as well, maybe it is time to check the valves to see if they need reshimmed. The carb can also be checked out while checking the valves and shimming if needed. One tip, for sure if you have the 2009, when you do the valves if you have to have the cams out and order shims, put the cam cap back on snugging a couple bolts, then put the cam cover back on snugging those bolts. That way the gasket cannot shrink up and require replacement. One other important note - when installing the cam cap, be very careful to make sure the cap is down completely in position. If it is not and the bolts are tightened it is possible to crack the cap - new head time. You can lightly tap it with the handle of a screwdriver to get it down flat on the head, then tighten the bolts in the correct pattern. It isn't difficult, you just need to make sure it is fitted down right, otherwise you risk expensive damage.

You know, a month and a half isn't much time. You do need to check the carburetor and see what jetting is. In spite of his know-it-all attitude KLXter does know about the jetting of the carb, although there are others too. Some of us simply used what had been tried and true before Dyno Jet kits were available and/or because we don't have air/fuel mix instrumentation or want to spend the money on dyno work. The fact is the jetting works, maybe not to the nth horsepower for the streets, but it works. D. Pippin has a great site that covers the use of Kiehin carb parts and a bunch of other tips for the KLX. It is for the 07, but the bikes are so close to identical in general and definitely in the engine, that the information carries over up to date, with the carb information not being applicable on the EFI bikes of course.

With the proper pilot jet and adjustment, the bike should start far easier. It may be unusual, but my brother and I did the jetting as described on Pippin's site, including the 2.5 turns on the idle mix and all worked great, so we simply left them alone. I forget if we did the 40 or 38 pilot jet, but either one would work since we split the difference between his 2400 foot elevation and sea level, coming in at 900-1200 feet elevation. But that is just for us lazy people who just want to ride them, not supertune them for the extra 1/2 hp. The bike runs fine, pulls strong, and never bogged or gives me any problems and we spent some time in some serious deep sugar sand in Michigan a couple years back that would emphasize any jetting issues.

But after doing the proper jetting, getting everything right, do not be surprised if you still have some that exhaust crackle if you're running a slip fit muffler or full exhaust. The free breathing systems will allow it where a regular OEM muffler silences it.. As Mikuni assures us, it is not a problem nor is it harmful. I've heard it at races, as well as on the street, my own KLX650C with a full Baja Designs exhaust has rather nice crackle in spite of the jetting being fine. My stock muffler KLX250 probably has some crackle, but it is drown out by the muffler/cat convertor. Funny part to me, which I mentioned before in other posts, in my research I found that a lot of car guys want to know how to increase the exhaust crackle on their cars.

Another thing is disabling the compression release. If you get into the valve cover you can disable the compression release, which is essentially unneeded on the electric start 250. That will also help starting, since it is no longer losing any of the fuel mix lost when the compression release is working. There are a couple ways to deal with it, but since I don't want to catch more crap from the grand poo bah, I will tell you to take the spring off and that will disable the compression release.

With jetting, either per Pippin or per KLXter, along with the compression release being disabled, the bike should start WAY better. One more note, the bike should idle around 1200+ rpm. I think mine's around 1250-1300 rpm.

 

KLX678,

Thanks. Shimming the valves looks like a daunting process for someone like me with little knowledge. I feel more confident cleaning the carb. Its def going to be a busy weekend for me. My exhaust arrives friday and plan on installing it along with the KLXster rejet setup I Im taking his advice due to the hybrid use of dyno jets / stock components and no drilling (no shade thrown at those who do).

Also Dpippin is a cool site.

 

Don, went back and re-read your posts.. Forgot that you and I have talked about your impending mods... Remove the air injection system and properly cap all its' remaining connections. This is also a case of "do it right, do it competently" on the first attempt - and it is done forever. without ever causing trouble. I had to make several trips to the hardware store to procure proper caps..

DIsassemble the carb, clean it and verify that all passageways will flow carb cleaner. Install a #40 pilot jet along with the DJ140/K152, DN0228@1N, on a stock slide spring and stock lift port, check fuel float level, set fuel screw to 2 out, put the airbox lid in the attic, bolt on the PC4 , reassemble the carb correctly.

Do this correctly without faulting, and you'll have a "new bike" to ride..

 

Thanks man. Really looking forward to my bikes performance after this! Ill keep you posted.

 

https://www.kawasakiforums.com/forum...a-model-23830/

Is the above post an accurate depiction of how to remove the air injection system?

 

Don, this may not apply to you but I want to make something clear here. An adjustable fuel mix screw has its place and this is not always a "set it and forget it" item. I regularly ride in a day from 4000 ft to 10,000 ft elevation. At the higher elevations, it has made an appreciable difference to lean out the idle circuit when running up high at the low-end of throttle input. I like my Kouba screw and used it (before going pumper), and the standard setting for me at 3000 is feet was a 35 pilot jet at just a little over 2.5 turns out. At high elevation, it would be turned to 1 to 1.5 turns out. A couple sharpie marks on it helped me find 2.5 when back down into the valley.

YRMV