I haven't seen any concrete evidence on the sizes of the jets, Keihin Vs DJ. There have been a couple of charts posted on this site with jet size comparisons although they are just that. They don't take into account the length or flow characteristics of the jet. (The important stuff.) The best evidence I've read was some home science done by a member on the ADV forum who tested some jets (keihin and DJ) for their flow and concluded for a given size they both flowed then same amount of gas over a given time. (He used #132 keihin and #132 DJ if I recall.)
What you must remember is you are jetting YOUR bike. Although there a lots of other recommendations from forum members on their personal set-ups you'll have to do the leg work yourself. As for DJ Vs Keihin, the jets are just numbered for reference. Take your pick on which brand to use, either or, you'll still need to have a feel for how the bike performs.
Savage. A couple of WOT runs over a given distance should see you with the best main jet. Time the runs. The best time = the best jet. Used this method when I chose the #138 main I'm using. Consistently faster times over the #135 main yet almost the same as the #140 main. So much bog with the #140 main so it was the #138 for me. TBH I could FEEL the difference between the #135 and the #138, the time test just reassured my choice.

As for the spring. You have the DJ kit so you have a spare. As I understand the DJ kit spring for the 09 KLX250S is 1/2 inch shorter than the spring that comes with the kit for the KLX300R. Depending on which spring you have you could trim one down. You'll always have the OE as a spare. Do you get it? ( the spring in the 09 kit is already 1/2 inch shorter, DON'T trim it any more.)

 

Also take into account hes in Sri Lanka. I'm quite sure its hot and humid there pretty much all the time and hes at or very near sea level at all times. Plus hes running a stocker air filter.

All important things to take into account.
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HERBALAIRE

 

I'm not recommending jetting, just that I don't think there is all that much difference in sizes Keihin vs DJ. If that were the case, my '09 wouldn't run at all right now with a 128 main DJ when my '06, same engine and carb essentially, with a 128 Keihin ran exactly the same beins that the DJ is supposed to be so much larger. It may in fact be larger, but I bet not enough to tell the difference. moot point really.

 

Oh ok.. Thats interesting.. Now Im confused lol

Oh ok, I will try timing the #120 Main and the #128 after that and so on..

And I didnt get a slide spring with my DJ Kit for the KLX300R?

And for setting the fuel screw, how do I test different settings on the fuel screw? Its now set that it idles perfectly and all.. But how do I make it affect my performance?

Yup..

Oh..

 

If theres one thing I've learned this engine and carb are friggen goofy. It seems moody almost. Either that or just hyper sensitive, and quite possibly almost impossible to keep jetted perfectly unless your somplace like where you live where there is a constant climate year round.

My bike must have been spot on or slightly rich, because yesterday it was like 60 or so..I'm not actually sure what the temp was but it was around there. And today it was 50 and my bike ran SO much better. I'm guessing it was a bit on the rich side and its spot on now, or that ever so slight lean condition where its not lean enough to cut out but enough air to make it have a hell of a combustion.

And I would follow that conversion chart between DJ and Keihn. I have a UNI filter, snorkel removed, backfire cage removed, and (if it makes a difference) smog stuff removed, and crank vent drilled, in 50 degree weather and I have a #130 main, N1TC needle at the middle clip (3rd down), and a 35 pilot approx 2 3/4 turns out. And its running like a champ. That makes perfect sense being I don't have a pipe on becuase a #130 Keihn is a DJ #126. Almost everyone here running a #128 DJ (which is a 127.5 Keihn) has the snorkel removed and at least a slip on. Oh and I keep forgetting, my slide is drilled out to 7/64''
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FAKE WEED

 

+1

 

well if a DJ 128 is equal to a Keihin 127.5, that explains why my '09 runs identical to my '06 with a Keihin 128.

 

No a 128 DJ is the same orafice size as a 137.5 Keihin.

"Many things affect fuel flow through a jet of the same orifice size. The entry and exit tapers of our main jets differ from those of other companies. Due to this, the fuel flow changes as a function of velocity through the carburetor venturie"

"The Dynojet main jet hole size is measured in millimeters. For example, a DJ142 has a 1.42mm hole."

"A Mikuni 140 has 140 cc of fuel flow per minute"

"We're not sure where the Keihin scale comes from."

 

I depends, in large part, upon the total inner surface area of the jet.

From a seat of the pants standpoint, the Dyno Jet needle has a noticably different taper, so the amount of overlap into the main jet's range may be different from that of the Keihin.

 

Well, when I had the DJ#132 in my carb, I also tried the Stock Needle and the response became better..Do you think I should try the stock needle with the #120? And raise it with shims if needed? Heres a video of me doing wot on sunday.. That stretch is 1/2km stretch.. Maybe a wee bit less.. I did manage to hit 123kmph once that day..But on the video I did hit 116kmph..

Click Here


Do you guys think that enough (123kmph) top speed for a 13t Counter Sprocket? Because another thing I noticed is, I gained 40kms for a full tank of fuel compared to the DJ#132 Main..