I bet its b/c its now a 50 state legal machine. So it'll work w/ the smog stuff.

Now I'm curious if #2152 works better. I bet not...I'd still go w/ #2206 since the bugs have been worked out and you know that others have made it work.

 

Is it possible that the 300 carb has a different spring rate that may allow quicker throttle response and the 250 kit spring is like the 300??
-or is it simply a different length, and if so, what is the performance or efficiency gain with changing the length ??
Just trying to understand.
Thanks, Glen

 

*sigh* sometimes I wonder if you disagree just to disagree. Who says the needle can't be more tapered? I know for a fact several other companies make needles which have 5 tapers to them.

The jets ARE DIFFERENT, did you even look at the kit contents? I've been jetting bikes for over 20 years, do you think I am so stupid to not know the difference between different jet sizes? Clearly the actual jet thread size can't be different, but man, sometimes the things you say....there are different sized jets and more of them in the 250s kit when compared to the 300 kit.

If you do not know anything about the spring then why are you saying to cut the stock spring, how do you know it is shorter and not longer or perhaps the replacement spring is softer. Stop giving unfounded and untested suggestions that could screw someone over if they listened to you.

The rule on pilot jets is, once you go under 1.5 turns you need a smaller pilot, if you go over 3 turns you need a larger one. So at three turns out as suggested you are on the bubble as to getting a larger pilot, it will not hurt. But the point is, the KLX300 kit says 2.5 turns out, the 250s kit says 3 turns out, same carb, so something is different over all and it confirms what a lot of people here have found, a larger pilot works better. Just marketing? What the hell are you talking about? Marketing what? Marketing screwdriver turns? Is someone here in the pilot jet business and they are making a million dollars selling larger pilots to us?

 

This gives some insight into what jetting the earlier model KLX's were like.
#35 Pilot and #132 Main. These bikes put out about 30 horses in 1994!

 

I installed the 300 jet kit on my 2009 nine only to find out they came out with the 2152 kit a few days later. the 2206 kit worked very well but I just installed the needle and spring from the new kit and the bike seems to be even jumpier and have more power. at least I can get a wheelie going with stock gearing.

 

Im thinking the same.....Urgggh....

I got my finger on the checkout button...Which to choose...2152...Might be the smogged kit...Or like stated above..The 2152 mixed with the 2206 was even nicer......

 

The emissions stuff has no effect on the jetting,the only exception is making the crankcase vent larger, but that too doesn't effect jetting. Get the kit for your bike.

 

Good lord people, dynojet finally makes a jet kit specific for our bike and you are questioning whether to get it or one designed for a very similar but different bike. Seems like a no brainer to me, I'd get the new kit with the spring and stuff.

Who do you think knows more Dynojet or a keyboard commando in Iowa.

 

When it comes to buying a kit for a ECO friendly bike and have it maybe pass a 50 state inspection....Thats where I have my doubts....A pure dirt bike kit might be more peppy and non eco friendly...

 

no drilling of slide in new kit. the only additional jets to the 250S kit are leaner than the factory 118 main. so basically, the only difference between the two kits are the needle and the spring in the new one.
the 300 jet kit added three horses to the stock 20 whereas the 250S jet kit only added one. that should tell you something right there. the 300 kit was way more effective. that is taken right from dynojet's website.
isn't this common sense? the new kit has to enable the bike to remain emissions friendly and legal vs. the 300 kit that doesn't. it's a given the new kit will not be as performance minded, at least it is to me and dynojet's final numbers back that up.
some may call me crazy when I say this is purely marketing, but I firmly believe that. there was no jet kit for this bike previously. now, since the '09 is out and ungodly popular, DJ saw an opportunity to put a dynojet kit on the market to sell to these buyers who do not know that the 300 kit will drop right in offering more performance as DJ documented themselves. it appears to be working for some (the marketing). keyboard commando out.