Hi there.

I just picked up a 2007 KLX250 that is completely stock except for a set of fat bars and risers.

I understand that I need a skid plate, hand guards, etc., but it is the jetting and air box mods that I am not sure of. I have spent a few hours reading threads on it, but that just left me confused!

I want the bike to be quiet, so I want to keep the stock exhaust. I don't mind drilling into the baffle to let it breath better, but I don't want to change it for now. I will also be running the stock air filter.

So, since I am using the stock filter and exhaust, do I bother to rejet? I understand that the bike is lean from the factory, but enough that it needs to be adjusted?

Anyway, here is what I am trying to get at: At an elevation of about 1000 ft, what mods should I do to make the bike run at its peak performance while using the stock filter and exhaust? I am not looking to increase the power, just in making it run well.

Thanks for your help on this.

 

If you're keeping the same slip-on and not doing anything to the air box there is no need to rejet. Maybe after you do your exhaust mod, but ride it first and then go from there.

 

Mr.C?

 

Short of some dyno runs or other super-precise methods to fine tune jetting, you can do what has been established as the best cheap mods for the KLX. My brother found a site where the rider had his information and did the mods on his 07. He sent me the document when I got my 09. It is pretty much "Plug and Play".

Click on the link in my signature to get the information. I'm running stock exhaust and intake, except the jetting recommended, the 220 snorkel, and a Dial-A-Jet fuel adder. I've run the Dial-A-Jet since the 80s, had them on my Honda Nighthawk S and put one on my 650, adds fuel under lean vacuum draw to fill in and smooth out jetting flat spots. My brother ran his 07 first without the Dial-A-Jet, ran better, but still had some flat spots. I sent him a kit I got for my SR500 (singles all use the same kit), he installed it, and said it definitely ran better, carbing smoother.

You will find the bike starts better and warm up is much quicker. I also did the Marcelino cam timing mod, also linked in my signature, and my bike starts almost instantly, coming off choke in about 30 seconds or so in normal weather. I disabled the compression release while in there, the 250 doesn't need it. It totally contradicts the hard starting reputation of the KLX, it is clear the hard start/warm up is due to jetting.

Do the jetting and snorkel, you'll find it better performing than stock for "plug and play". Add the Dial-A-Jet dropping the main jet one or two sizes at the same time, and you'll have better response yet. The Dial-A-Jet is an external installation that isn't difficult.

The KLX300 jetting from a Kaw dealer is under $100, part numbers are given, and is quite literally "plug and play". It will improve the bike starting and performance. Nice part with the Kawsaki parts are they are common Mikuni parts, the information on Mikuni parts and jetting progression is well documented in the Mikuni handbooks found on their site as well as Sudco and numerous others. Plus should you ever need to change jetting it is quite easy to refer to the Mikuni manual and get the jets almost anywhere.

The Dial-A-Jet is $80 and will compensate for future modifications, like my brother adding a KLX300 exhaust and cooler temps or lower elevations causing leaner conditions. I am at 900ft, so pretty much same as you.

 

Welcome to KF and to the 2007. Good year!

Think twice before modding the stock exhaust. Drilling the baffle was a popular mod early in this bike's run, but not so much now. I think if you look around, you'll find members reporting that it did little if any good and it did destroy the spark arresting functionality.

How does the bike start and idle during warmup? Popping off the epa cover from the fuel screw and backing it out a little may help. It is often at around one turn out stock, backing to around 2 to 2.5 turns can be a nice improvement.

 

I ran an uncorked stock exhaust, removed snorkle, DJ124 main, DJ needle/3n, DJ spring, AF 2.5 turns. Ran perfect from sea level to 2500'. Very quiet compared to my hindle/no lid setup, but down on power big time.

 

Yep! It is me. I tried to join with that handle, but the system said the name was being used. Oh well. Is this Suprf1y?

Thanks for the ideas so far, folks (and not flaming me for not searching properly ).

It is still winter here, so I don't know the characteristics of the bike in its stock form yet. I will certainly ride it a fair amount in its stock format once the snow leaves.

Upon further reading about the stock exhaust, I certainly will not be drilling the exhaust. I want the spark arrestor intact. If anything, the most I will do is put on a larger exhaust tip to open it up a bit.

 

Yup, that's me. You have two choices for jetting, the OEM 300 parts, or the Dynojet jetting kit. Probably more use the DJ kit. I went OEM on my 07, but DJ on this bike. I wasn't thrilled with the way it ran, so I've pulled it out and gone to the setup linked by KLX678. It seems that the DJ jets may not be big enough for my setup, based on testing by some of the members. You will find that the DJ jets are numbered/sized differently than OEM. The OEM parts are $40 from the dealer. Other things you may want to do are wide pegs (some on ebay for ~$20 that I like) and maybe a better headlight bulb. If you're going to be using it off road a lot, rim locks are a necessity. My build is here, if you're interested.

2009 KLX 250s dual sport| Sprockets | forum |

You'll see my solution to the rim locks, and why I did it that way.

 

Interesting. Are those screws actually biting into the tire, or just pushing in on them to stop them from sliding on the rim?

I am also try to lower mine a bit. I can just flat foot in now, but wouldn't mind it a bit lower for when the ground is uneven.

 

The screws are sharpened on the end and biting into the sidewall of the tire. I've probably run about 8 hrs of pretty hard hare scramble loop at speed and no problems. If you want, I can make you up a set of lowering links like the SS ones in that build thread.
Some info on links here

https://www.kawasakiforums.com/forum...le-info-31135/