Hello everyone. Newbe here. Bought a used 07KLX250S with 859 miles on it. It already had a 300 cylinder and piston, Two Brothers M7 slip on with tip,K&N filter and very mild jetting. I have put about 200 miles since I bought it. It runs OK but I have thought it was running very lean so yesterday I removed the carb because I was curious about the jetting. The main is a 120, pilot 38 and the mixture screw was 6 (yes 6) turns out! I went to remove the plug and backed it out with just my hand holding the factory plug socket! The plug is pure white and the threads were sooty all the up to the washer. I am planning on either ordering the typical KLX300 parts or a Dynojet kit. I think the bike has way more power potential than it has now. Anyone here have any opinions as to where I should go to on the jetting?

 

Welcome, try search function theres quite alot of reads for your setup.

 

Hang on because you will be flooded with opinions soon. I'll throw in my .02 cents worth. The Dynojet KLX300 kit will give you the best needle. However, there is a needle you can buy from Kawasaki that is supposed to provide the same performance. Others can chime in with the part number. It's NT1S or something like that. I'm running my DJ 300 needle on the 4th clip from the top. Guys run anywhere from the 2nd, 3rd or 4th notch with good results. A lot depends on what other mods you've done (airbox lid removed, exhaust, etc.) Depending on your altitude I wouldn't put anything less than a 128 main jet in your bike. I run a 132 main at sea level and get great performance. Others run 135 and even 138! Your pilot jet is right on - IMO. Try 2 or 2 1/2 turns out on the A/F screw for starters. WestOzKLX, 09KLXOwner, Nobrakes and a host of others are great resource for jetting and any other info you need. They all helped me get my bike dialed in. In summary, if I were to suggest as baseline setup for sea level to 2000 feet, I'd put in the DJ 300 needle or similar, drill the slide as per DJ 300 kit instructions, 132 main jet, 38 pilot, A/F screw 2 1/2 turns out. Experiment from there if needed.

 

OE needle N1TC with clip and collar, OE Keihin #138 main jet (cheapest option.)
Dynojet kit for the KLX300 (all parts in one box solution.)The largest main jet in the DJ kit is only a #132 though.

 

Thanks for the replies everyone. I had thought about starting with a 128 main and a 40 pilot jet. I am located in Central Arkansas at 350 feet above sea level.

 

welcome to KF

 

WestOZ-- don't the numbers differ between Keihin and Dynojet though (i.e. Keihin #138 main doesn't equal a DJ #138)? I'm not sure where I got this chart (off here somewhere if memory serves) but it shows the Keihin #138 (#137.5) would be a DJ #128:

Width------Keihin # -- DynoJets # -- Mikuni #
0.0350---- 92.5--------- 92----------- 86.3
0.0360---- 95----------- 94----------- 88.1
0.0370---- 97.5--------- 96----------- 90.0
0.0380---- 100---------- 98----------- 91.9
0.0390---- 102.5------- 100---------- 93.8
0.0400---- 105--------- 102---------- 95.6
0.0410---- 107.5------- 104---------- 97.5
0.0420---- 110--------- 106---------- 99.4
0.0430---- 112.5------- 108--------- 101.3
0.0440---- 115--------- 110--------- 103.1
0.0450---- 117.5------- 112--------- 105.0
0.0460---- 120--------- 114--------- 106.9
0.0470---- 122.5------- 116--------- 108.8
0.0480---- 125--------- 118--------- 110.6
0.0490---- 127.5------- 120--------- 112.5
0.0500---- 130--------- 122--------- 114.4
0.0510---- 132.5------- 124--------- 116.3
0.0520---- 135--------- 126--------- 118.1
0.0530---- 137.5------- 128--------- 120.0
0.0540---- 140--------- 130--------- 121.9
0.0550---- 142.5------- 132--------- 123.8
0.0560---- 145--------- 134--------- 125.6
0.0570---- 147.5------- 136--------- 127.5
0.0580---- 150--------- 138--------- 129.4
0.0590---- 152.5------- 140--------- 131.3
0.0600---- 155--------- 142--------- 133.1
0.0610---- 157.5------- 144--------- 135.0
0.0620---- 160--------- 146--------- 136.9
0.0630---- 162.5------- 148--------- 138.8
0.0640---- 165--------- 150--------- 140.6
0.0650---- 167.5------- 152--------- 142.5
0.0660---- 170--------- 154--------- 144.4
0.0670---- 172.5------- 156--------- 146.3
0.0680---- 175--------- 158--------- 148.1
0.0690---- 177.5------- 160--------- 150.0
0.0700---- 180--------- 162--------- 151.9
0.0710---- 182.5------- 164--------- 153.8
0.0720---- 185--------- 166--------- 155.6
0.0730---- 187.5------- 168--------- 157.5
0.0740---- 190--------- 170--------- 159.4
0.0750---- 192.5------- 172--------- 161.3
0.0760---- 195--------- 174--------- 163.1
0.0770---- 197.5------- 176--------- 165.0
0.0780---- 200--------- 178--------- 166.9
0.0790---- 202.5------- 180--------- 168.8
0.0800---- 205--------- 182--------- 170.6
0.0810---- 207.5------- 184--------- 172.5
0.0820---- 210--------- 186--------- 174.4
0.0830---- 212.5------- 188--------- 176.3
0.0840---- 215--------- 190--------- 178.1
0.0850---- 217.5------- 192--------- 180.0
0.0860---- 220--------- 194--------- 181.9
0.0870---- 222.5------- 196--------- 183.7
0.0880---- 225--------- 198--------- 185.6
0.0890---- 227.5------- 200--------- 187.5

 

Yeah man, we've been here before. Someone on the ADV site did some home science with the Keihin and DJ jets. The long and short of it is that over a given period of time they flow exactly the same amount of gas for a given size. I think the #132 was the initial test if I can recall. It's on the Long term KLX thread if you want to search it, about page 100 or so.

 

I had the same exact thing! Everyone says how these machines have a 118 main and a 35 pilot in them and mine "supposedly" has never been torn into yet when I looked in the carb I found a 120 main and a 38 pilot. And on the fuel screw, I said I lost count because I ended with what I thought to be somewhere around 6 turns and figured I must of got confused as to what I was seeing in my low light garage...so I just said I wasn't sure. Because I wasn't. But now that you have said that it makes me think. Also, I turned my screw all the way in and tried backing it out. I can't get it past 2 5/8's of a turn before it stops. Not a dead stop, like it ran out of space, but just gets real hard to turn. Thats one of the reasons why I figured I couldn't have been right about the 6 turns, because If I can't turn it much past 2 1/2 turns then how could it have been 6? I of course did it a few more times and got the same thing.

I'm still working the kinks out of my heap. Best of luck to ya boss.
________
Threesome bathroom

 

Well I finished my re-jet project today. I did the N1TC needle, clip second down from top, 128 main, 40 pilot. A/F mixture 2 turns out, removed the backfire screen and drilled out the small hole in the airbox for the crankcase vent. I seems to run OK so far. The only noticeable difference so far is that pops more when decelerating than before. I have a loud *** Two Brothers M7 cannister on it with a reducer tip. I don't really notice any drastic power improvement but maybe it's becasue I already have a 300 kit on it also. I need to put a few miles on it and report back later.