Just got done putting my Leo Vince X3 slip-on onto my 09 SF. It sounds great, looks great and I could immediately tell the difference of that along with the uni filter I added at the same time. I will add Pics and a video link tomorrow.
Here's two questions about it.

1) Is it important to have the arrester on? (the x3 has four options, 2 with arrester, 2 without)

2) The directions say a jet kit is not needed, does it harm the bike if not used? If so, what jet kit is the right one for just a slip-on exhaust?

 

The addition of the Uni filter you added along with the exhaust could result in your bike being too lean. Which could lead to expensive problems.

It's possible in some instances to add an exhaust without re-jetting. But with the increased air flow of the new filter, I would consider a re jet.

If you're not riding off road, the spark arrester isn't required. I take my SF on forest roads from time to time, and I like to be legal.

Dyno Jet

KAW 09-10 KLX250SF 2182


2009-2010 Kawasaki KLX250SF
Stage 1 & 2

STAGE 1
For mildly tuned machines using the stock airbox, with stock or K&N filter.

STAGE 2 For mildly tuned machines using stock airbox with intake snorkel removed, with the stock or K&N filter. Both stages may be used with a good aftermarket exhaust


http://www.dynojet.com/jetkits/motorcycle/kawasaki.aspx




JMHO

 

In my opinion, a KLX250 needs a jet kit (or jetting mods) regardless. After putting mine in, I was more than happy with the power, I am passing on a pipe.

It really woke up my SF.

 

Is it really possible to cause damage by just adding a slip-on and replacing the Air filter without re jetting?

Added:
Leo Vince X3
Uni Air filter with no alterations to the box


I am planning to re jet, but I was going to wait a couple of months to do so because of an upcoming move. Can I really harm the bike during this time by using it as a daily commuter?

 

Too lean can detonate the top of your piston and put a hole in it. The bike may run OK until upper rpm and then you quickly lose power. You don't get a lot of time to determine that as loss of power could indicate it's too late.
I am looking at getting a KLX250S in the very near future and am not familiar with jetting sizes here, but when I did K&N and a free flowing silencer on a carbed street bike using stock air box, usually went up one or two on the main, one on pilot and opened up the mixture screws about a half turn (depending on bike).
I understand that increasing the bikes ability to breathe allows it to rev free and get to it's power range (whatever that may be) quicker, not necessarily producing more than margin power gains. With this bike it seems like you either go stage 1 or big bore. Once you pull or modify the air box, you may as well get rid of it and go all in with the mods or you'll be playing jetting games a lot.
I'm sure someone here will have just the jetting combo you need to dial it in yourself.
Personally, I've never cared for Uni filters and prefer the K&N OE replacement or pods for air flow and build quality.

 

Hope this isn't a silly question. Does the carb have to be removed to install new jets and needle, or can the carb be losened and rotated 90 deg. after disconnecting the cables and lines? Looks like time consuming job to remove. Heading to Death Valley at the end of Jan. and would like to have the bike running sharp.

thanks

 

Yea you can just rotate it. You will have to take both throttle cables and the bracket that clamps them to the carb off. While yer in there drill the cold start jet out. Dont know if you can do that without pulling the carb off though. You cant get a true 90degree rotation out of the carb while in the bike. tight fit.

 

Thank You. That's what I wanted to hear.

 

I installed the dynojet kit, I'd say it would be easier to remove the carb. The kit also comes with a different diaphragm spring. It's difficult getting the carb back on, trying to get it into both rubber boots, but a little patience and it will go back in.

Remove the external fuel valve with the tank, unless the tank is bone dry.

And take pictures of the hose routing.

 

I can't find a k&n filter for the 09 klx250sf. Is there a K&N filter that is able to be usedon the 09s. I did just ordered the dynojet kit, and I will have that installed next week when it arrives. Until then I will just let the bike sit.