Hello fellow members. I just took home a new 2009 KLX250SF with 3,000 miles. The previous owner took good care of it and I'm very excited to own her. Mods done so far. Took the huge mirrors off. Replaced with small left side mini. Took the rubber footpegs covers off. Fender eliminator kit. Plan on taking the front reflectors off as well as the little rear pouch. Getting Shinko 244 tires front and back.
So as far as advice from you guys, I would like to add a slip-on exhaust, re-jet, and mod the airbox with new air filter. I really hate how quiet this bike is with the stock exhaust and I would not mind the extra HP. So what brand slip-on along with jet kit should I buy? Not sure what jet kit goes with what brand Slip-on? I want something on the loud side, deep and throaty to let cars know I'm coming. Cannot live with the stock exhaust sound. Did some searching but have not heard much of slip-on, jet combos from the archives.

 

See the links below on my signature line.. And the sticky on exhaust choices..

 

FMF Q4 seems popular. It's what I have and it's pretty loud. I'm getting a quiet core insert for it to quiet it down a bit and prevent setting the forest on fire.

 

Ahh, all FMF slipons have a spark arrestor and are forestry approved.. Unless yours has been removed..

 

Ok FMF powercore4 slipon it is. Calling dynojet to get the right jet kit. Do you guy recommend removing the snorkle ? I'm running it 50/50 onroad offroad. What air filter?

 

Yeah, the FMF Q4 I have came with the KLX250S I bought and it has nothing in there. I've heard it's pretty easy to lose them on the trail or maybe the previous owner just removed it to make the pipe louder. I'll be using blue locktite on the screw and high temperature silicone around the insert rim when I install the new one I get.


I'm pretty sure the jetkit you get will either suggest you remove the air box snorkel or the air box lid. Some people are also running KDX snorkels in their KLX250S. My used KLX250S came with a FMF Q4 and the air box snorkel removed.
This thread was an interesting read for me as I'm still wondering if I should run without snorkel or get a KDX snorkel.

I'm going to be replacing my air filter with a Twin Air filter (151109 is what you need for a 2009 KLX250S). From the research I have done, these seem to be the most popular. Uni is another good filter but where I live the Twin Air is only a couple bucks more so I figured I'd go with the more popular one. I've heard the K&N filters (KA-1287) give the best air flow but most people don't recommend them for off road use since they don't filter as good. I also ride about 50/50 and decided against the K&N filter for that reason. It's also really expensive at about three times the price of the Twin Air and you also need specific K&N oil for it (as it's not a foam filter). If you want the best performance, maybe look into getting the K&N filter and a filter wrap.

 

I run a K&N, lidless with a Two Bro's slipon. I ride lot's of trail's mostly logging roads and singletrack, I just wash the K&N every couple of month's.
1/2 of my daily commute is logging road.
I went with the Kawi needle and Keihin jets as personally I dont see the point buying the entire DJ kit just for the needle.

 

Guys, regardless of exhaust choices, as long as the lid is on the airbox (with any snorkel, or without a snorkel), you use the DJ 2152 kit as per instructions..

The big power is with running the airbox lidless (plus performance exhaust slipon/system) - but lidless requires a whole different carb setup - and the DJ kit(s) cannot be used as per their instructions..

Rage, the N1TC will and does work, but it is very short with an aggressive taper, so it goes "full rich" very quickly.. Still, with a stock spring and lift port, and the clip at the top notch, it does work..

 

What kind of gains can I expect from this kit with no mods except for opened up factory exhaust? Is is worth doing without changing other stuff?

 

I've seen people do dynojet kit on stock bikes so it must be worth doing. Apparently the bikes are pretty restricted due to emissions control so jetting your carb should spruce it up a bit. The Australian KLX250S is more powerful from the factory compared to the North American ones and I think it's only the jetting that is the main difference. The service manual says the AU model has a different main jet, starter jet, and needle.