Hi guys, I've been reading these forums for the past few months and gained a pretty good understanding of my bike from all the great info here.

I purchased a completely bone stock 2011 klx250s in September that had 5kms on it, couldn't pass it up so I snagged it. PO had left old gas in it but said he had taken off the float bowl and cleaned all the varnish out of the bowl and jets. Once I got on the bike throttle response wasn't very crisp at all, had cold starting issues and also would stall from idle when throttle was applied but would idle fine.

Long story short I purchased a DJ2152 kit installed it to Stage 1 specs on my stock bike i.e. Main jet DJ116, new needle 3rd notch down from top with 2 spacers, new spring, drilled out AF mixture screw plug set it to 3 turns out and cleaned the pilot jet while I was in there. I'm at Sealevel. Put it all back together just fine bike fired up real nice, good throttle response, starting it was way easier and seemed to have good power.

After using it more I realized something is not working properly, if I hold throttle open revving between 2 and 3000 rpm it kind of chugs then will stall without fail. If throttle is held open above 3000 rpm no issues, or if I blip throttle hard from idle no issues. Bike will also stall on de acceleration while down shifting into 1st gear as well. I think I'm correct in saying that the pilot jet is responsible for idle to roughly 3k rpm? My pilot jet is a stock #35. Another thing that I'm going to tinker with is the AF mixture screw, could this be the potential cause of this?

Long post and I apologize but I wanted to be concise with the info I provided, thanks Dan.

 

Certainly sounds like you're on the right track. The pilot screw adjustment is suspect - though at 3 turns out you should be fine - even at sea level.

There is no AF mixture screw on these carbs, only the fuel screw that lets more or less fuel in for the pilot circuit. Screwed all the way in is no gas, all the way out is all the gas your pilot jet is willing to give.

Check for leaks around the carb spigots / boots too. Also, a 116 is preeeetty small for running at sea level, even with the stock exhaust and snorkel on. It might be worth bumping that up, thought I don't necessarily think that's your issue.


Welcome to the club!

 

Welcome Dan.

Think of the pilot jet primarily functioning from 0 to 1/8 or 1/4 turn of the throttle, as opposed to RPM (although those are likely close in your situation).

Did you put the 2 spacers on TOP of the needle clip to help keep it from bouncing around in the holder? Or under the needle clip thereby raising the needle more? The first is correct IIRC.

Your pilot may be plugging again. Try opening the choke/enricher in your 2 to 3000 rpm test and see what happens.

A number of sea-level riders go to a size 38 pilot jet. You can determine if this is necessary by adjusting the fuel screw for best/highest idle. If <1 turn out, you need a smaller pilot (not likely for you). If >3 turns out, look towards a larger pilot jet. Do some searching on Jetting.

There's a load of information in the FAQs: https://www.kawasakiforums.com/forum...q-links-30733/

 

Thanks for the replies guys.

pwjm when you say carb spigots are you referring to the hose tubing lines coming off the carb? The boot I assume you mean the air intake boot collar and engine collar clamp? You are thinking I have a potential vacuum or air leak I assume?

IDRIDR I did order a oem #40 pilot jet maybe I will try that, reason I did not install it when I did the jetting was I thought it might be too big. I'll turn the fuel screw out another 1/4 turn see how I fare and I'll all try the 2 to 3 rpm with choke open, in your opinion what will that tell us? Points to pilot?

Thanks again guys. I do enjoy my bike.

 

If the bike is sputtering out at low throttle opening and opening the choke keeps it running, that is an indication that you may have a problem with the pilot circuit.

Some owners use a #40 at sea level. A big pilot will make it easy to start and it will run okay, but it won't have the low-rpm snap that a properly sized pilot with tuned fuel screw will. Going #35 to #40 is a pretty big jump. Unless you're way lean with a #35, I'd suggest trying a #38. See the jetting spreadsheet in the FAQs for other setups.
https://docs.google.com/spreadsheets...Dnc/edit#gid=0

You'll notice a lot of riders are using #35 at low elevation. IMO based on what I see out there, going to #40 is likely too fat, but I'm a long ways away from sea level so take that for what its worth (not much). Klxster has done more actual dyno tuning than anyone else around here that I'm aware of. Check out some of his jetting threads.

 

Before taking your carb apart again check the float level.

 

Just an update, I first tried the fuel screw set it to 31/4 turns then 31/2 turns out respectively with the same results. Throttle held steady at 2.5 to 3000 rpm it starts to sputter then if i release the throttle it stalls. It also stalls using choke to get engine at those rpms. Next I dropped the float bowl and swapped out the stock #35 pilot for oem #40 I had. Here is where I found what might be the problem the float bowl o ring had a cut in it, might this be the cause of this sputterring?

Since I don't have a spare O ring on hand I went ahead with the #40 pilot and ended up with the same issue of the sputter to stalling.

 

I'm not sure what O-ring there would be associated with the float bowl, but the CVK carbs are very temperamental with vacuum related issues. It's a major reason a lot of guys do the "T mod" for their carb vents.

And yes, I was just referring to air leaks around the carb where it mates to the engine side.

You're going to want to fix that o-ring anyway, so that's a good place to start regardless.

 

Do you know of a location for specs on float adjustment?