Hey guys how goes it,

I am a new owner of an 09 klx250s and have been looking into mods for some time on the this site (alot of reading!!!). My bike has come along way in the last while and its been a blast doing the mods. I have been doing them all at once. The site has been great for info but I am still stuck on a few items. I can't decide on my last 2 mods. Is the crankcase breather mod really worth it and did you guys drill the air box or go with the reroute under the seat? The posts seem to go back and forth as to what is better or if it is even neccesary. Secondly did most of you remove the backfire sceen? Is it worth the effort to remove it "ie any performance gain". I would hate to cut all that out and risk a missed sliver of screen going in the carb for no gain in performance. Last but not least I am stumped on the pilot jet....leave it stock or go up to a #38 and if I do what is the partnumber?????? I can find part numbers for the #40 but the #38 seems to be a mystery on here. I have a kouba screw on order to try adjusting but my dynojet kit states that i should be 3 turns out with my present setup which is why I figured I should maybe try the 38 (dont want the kouba screw falling out). Thanks for the feedback guys its a great site!

 

https://www.kawasakiforums.com/forum...4&d=1229086262

This gives you the part numbers you need - thanks to WestOzKLX

 

I'm glad to see your having fun. Moding my klx was the most fun I ever had with a bike. Many days I'm sorry I sold it.

I did the screen with the carb rejetting- So I do not know how much it helped, but the bike is starved for air, so if you remove the air box lid- the next biggest restriction is the screen.
I also did the crank case vent- I ran it to the air box. I melted a hole in the box so I would not have pieces in the box. I can not say it helped but it did not hurt any thing.

The fcr pumper carb was the biggest change to the bike- It changed its personality. The BB 331 kit finely gave me the power I was looking for.

 

As you know removing the screen on the bike is not a good idea, for sure too many pieces can go astray. When I did mine I split the airbox into two pieces and removed the front half from the bike, it made removing the screen a breeze.

To remove it I used my dremmel and a bit called a Sabretooth which is like a reverse drill bit, that thing will cut through almost anything. To be honest though I can not say there is a gain as I did many mods at the same time, but Bill Blue did tell me it is worth doing and I trust his opinion so I have no regrets in taking it out.

 

Welcome to the forums. Glad you have found information on here helpful. Hopefully you can continue that for many years to come.

 

whats the advantage with going with the #38 pilot?

 

What I found was the bike didn't struggle to idle anymore, starting the bike when cold is a LOT easier, and when cold you don't need to have the choke on for more than 10 seconds before turning it off and she'll idle fine. The biggest thing for me by far was the idling though - especially at traffic lights on cold mornings when it was prone to stalling with the stock jet.

 

thanks for the info. I live in florida so i dont have to much of a problem with "cold". But what the hell i might just give it a try. I have noticed my sf is kinda of a pita to start when cold.

 

Well with your guys advice I did the backfire screen removal and the crankcase breather mods, with that all my mods are done for now. And the results: Well it was definetly better but not great. It reved way more freely and started much easier. The exaust itself smelled richer while running. But it had some popping on decel that was very minor so my jetting is perhaps still off. I had the spark arrestor out of the new pipe so I put it back in and the popping on decel decreased but was still present. So thought i would play around some more. I took the air box cover right off and took it for another run. It kind of bogged at little on the low end and at half throttle settings mainly at 4000- 5000 rpm (just barely). At full throttle the bike just took off !!!! It was insane. So here is what I am thinking. I am probably lean on the low end and getting close to spot on on the top end. Or would being lean throughout give more power when the throttle is full open? I am going to try a #38 pilot and see if the popping goes away and play with the fuel screw a little more. I think I am definetly still lean though. The exaust is not black in the end, more of a very clean brown. Should I leave the cover off and go from there as the power is much better or put it back on and rejet from there?

 

The first thing I'd do is try going to the 4th clip down on your needle (raise needle by one notch). I also think you can afford to go to a 132 main with the cover off. Being slightly lean of the top-end will infact give that launch you're experiencing, but it might also give you heat damage over the long run.

Good luck and report back with results!