your klx250, exhaust & jetting

[matt3357]

i was thinking maybe it would be good to have a list of people who have modded their bike and their current jetting settings, perhaps a sticky? something like:

1. your exhaust

2. any air intake/carb mods

3. your altitude

4. jetting settings

5. how close to perfect you think it is, rich/lean, and the conditions you usually ride in (dry summer/ice winter's)

[buggs bunny]

that's an excellent idea,"indy wr450" already did that for the wr yamahas.

it helped me a lot without asking lots of questions on TT

[lostnite66]

For 2009 KLX250S:

1. Full Muzzy exhaust, still corked

2. Uni air filter, KDX200 snorkle

3. altitude, don't know, but Dayton, Ohio can't be too high

4. Dynojet kit for 2009 KLX250S, don't know the specific settings, installed at the local Kawi dealer

I just got this done last week, and the weather has turned to crap, so I have very little riding time with the new parts, about 12 miles. Its runs noticeably cleaner, and starts easier. I have to mention again, it starts much easier even though the weather has turned much colder. It also warms up faster. When totally stock, it seemed like I had to leave it idle with the choke out for at least 3-4 minutes or it would stall out when I pushed it back in, and that wahen it it was still in the high 60s here. Now I leave the choke out for about half that time, likely less than that come next spring.

These changes haven't changed the KLX ito a race bike or anything. I still would likely get dusted by a WR250R or X in a drag race. But now it's running nicely like I want it to. I heard Muzzys are loud uncorked, I want to be at least somewhat stealthy, so I told the mechanic to install the pipe as is. It sounds deeper and is certainly louder, but not obnoxious. It feels like it runs a little stronger throughout the rpm range, buI don't know how much of that is the placebo effect, just think it's pulling stronger. The fact that it's louder could enhance that sensation perhaps. But it sure feels like it's pulling with more authority.

If the weather gets more decent soon, I'll try to hit this small patch of trails close to my house. There are a couple of tiny jumps that I had trouble lofting my front wheel on went I went over them with the bike being stock. That was never a problem when I had my KX125. We'll see how the newly modded KLX does when the opprotunity presents itself.

[cliffsta]

2009 KLX-250S

1. Stock exhaust ?

2. Removed the snorkel from the airbox lid. Stock air filter for now, soon to order a Uni. The 2009 DJ kit comes with a new spring so I guess that's a non-jet carb mod

3. Very low. ~60 feet ASL on average, probably a bit below at times. No higher than maybe 250 feet ASL at the very most.

4. 128 DJ main jet, stock pilot jet, Dynojet needle on the middle clip, fuel screw about 2.5 turns out

5. It runs great. If anything its a tad rich, it ran just fine in the summer. Since its winter it is running even better. But I think its pretty close to dead on, jetting-wise. Riding not far above sea level... so far I've ridden it in the heat of summer (over 90 degrees) and very cool fall temps, 40s in the morning.

[AlphaMike]

Finally got around to modding my wife's '09 KLX250 yesterday.

1) FMF Q4 muffler & Powerbomb header

2) KDX snorkle and stock airbox lid. Kouba adjustable fuel screw. Carb slide hole drilled to 7/64".

3) 4,300'

4) #125 main jet, #35 pilot jet (stock), N1TC jet needle w/ clip in middle position. (All jets from Kawasaki.)

5) Only had a half hour to try it out around town, but it runs great, with nice, crisp throttle response and no hesitation or bogging. Occasional light exhaust popping on the overrun. Temperature was 8 degrees Celcius (46F).

It might have been interesting to try a #128 main, but the bike ran great, and I really didn't want to pull out that carb again. Plus, we usually ride in warmer temperatures, and often up to six or seven thousand feet, so I'd rather it be a little lean than too rich. Best idle was with the fuel screw 1 1/2 turns out, so I guess that means the pilot jet is the right size.

I haven't ridden the bike a whole bunch, but it does seem to pull harder throughout the rev range. The bike sounds like a real motorcycle now, but I think it's on the loud side for street use around town. I'd definitely be embarrassed to fire it up at 8:00 a.m. for the commute to work. Love the sound for highway and offroad, though.

Winter has finally hit, so it looks like the bike will be stuck in the garage until March (we're heading to Moab for spring break! ? ).

[pakabo22]

'09 KLX 250S mods- two bros slip-on exhaust, dyno jet kit with 128 main installed, uni air filter with snorkel removed. Starts right up idles great and has alot more power mainly at mid range to top end. Runs smoother also. I ride from sea level to 4500 ft above with no issues. Very happy with these mods.

[kawarider21]

I have 'uncorked' my 09 KLX250s and it is a completely different bike from stock, they really are extremely restricted from new. I put a hole in the carb slide, installed a hand made Aussie exhaust called a staintune, #145 jet kit and took the airbox lid off. It really loves to rev now and I've had it up to 140kph.

[Punkenduro]

Murrieta, CA

09 klx250s

1. stock

2. removed snorkle

3. ~1000-1500 normal riding

4. 128 dj main jet, 35 (stock) pilot, dj needle

5. a bit rich, slight bog in high altitude (4500+)

[duckbutter]

I have an 06 klx 250 that I just recently bought with kn filter, air work, carb is jetted but I haven't gotten specs yet" the pipe is from yz 450 and previous owner polished it,, filter also from yz 450, it has absolute ton of power for a 250, very smooth and very, very stong. I will post pics later.

[cliffsta]

Murrieta, CA

09 klx250s

1. stock

2. removed snorkle

3. ~1000-1500 normal riding

4. 128 dj main jet, 35 (stock) pilot, dj needle

5. a bit rich, slight bog in high altitude (4500+)

Yeah I'm no expert but I think you might need to step down to a 124 DJ main. I'm at sea level, running a 128, and I think I might be a tad rich. Just my .02 IMHO etc etc.

[Savagekilla]

1. your exhaust

R.S.V Slip On (Japanese Made)

2. any air intake/carb mods

Carb Slide Vent hole drilled as per dynojet instructions for KLX300R.

3. your altitude

0-150ft

4. jetting settings

#120 DJ Main Jet, DJ Needle on 3Rd Position. Stock Pilot jet (#35).. And Koubalink adjustabler fuel screw..

5. how close to perfect you think it is, rich/lean, and the conditions you usually ride in (dry summer/ice winter's)

Pulls hard right upto Redline but has a small problem upon hard acceleration.. Not really noticable though.. Playing with the Fuel Screw Helps..

[dpippin]

i was thinking maybe it would be good to have a list of people who have modded their bike and their current jetting settings, perhaps a sticky? something like:

1. your exhaust

2. any air intake/carb mods

3. your altitude

4. jetting settings

5. how close to perfect you think it is, rich/lean, and the conditions you usually ride in (dry summer/ice winter's)

2007 KLX250S

Exhaust: stock (baffle drilled out)

Intake: stock filter, KDX snorkle

Altitude: 2400 ft (home) riding 1500 to 6000 ft

Jetting: (all OEM parts)

Main Jet 125

Pilot Jet 138

Needle N1TC needle (clip in second from top notch)

slide bleed hole drilled 7/64"

idle screw 2 1/2 turns out

Runs good, starts all the time, crisp throttle response, ride all year

[skline]

can anyone tell me about the slide hole being drilled to 7/32 and why...

[matt3357]

just thought i'd contribute:

1. your exhaust - FMF powercore 4

2. airbox lid off + twinair filter

3. sea level

4. 138 main, needle raised 1.5mm, drilled pilot to a 38, 2.5 turns out fuel screw

5. I ride early mornings allong the coast, so cold conditions. I changed to a kawa 138 main and raised the needle first, only removing the snorkle, i didn't check the spark plug but the bike ran fine and did not leave much carbon residue on the exhaust tip. the bike was still lean on idle and i could not get a kawa 38 pilot so i had the stock one drilled a bit, now the rear fender is black after a ride but the bike runs fine and response from idle is much smoother with faster response. just cant be bothered playing with the fuel screw

[deej]

132 and 40, runs flawlessly. ?

[5Rs]

2 Brothers slip on w/ P3 insert

FMF Powerbomb header

UNI air filter / backfire mesh intact

No airbox lid

DJ kitted 34 cvk

132 dj main 40 keihin pilot

Kouba screw 1.5-1.75 turns out

DJ needle 4th clip from top

drilled slide

crank case vent mod

sea level

Going with the bigger pilot jet helped remove the hesitation in the low to mid range.

Drilling the slide lets the slide move more freely. The newer kit 2152 has a shortened spring.

[rdhj]

reading all these have me wondering... the PO put in a mikuni 132 main and 40 pilot wit the stock exhaust and no lid or snorkel.. wondering if it is really rich and it should be set to 124 main...any suggestions

[MotorBikeDon]

reading all these have me wondering... the PO put in a mikuni 132 main and 40 pilot wit the stock exhaust and no lid or snorkel.. wondering if it is really rich and it should be set to 124 main...any suggestions

I am running a dj 124 with no air box lid, stock filter. Runs much gooder then stock...

[klxklxklx]

after looking at these jetting specs has any one finally found the magic jetting specs for the klx 250s... at sea level to 3000+

for a aftermarket slip on

no airbox lid

twin air filter

standard fuel screw

atm im running a #128 dj main and dyno jet needle 3rd groove with #40 pilot 2 1/2 -3 turns out and still not not feeling dialled in.

bike is now stuttering very badly at walking pace in first gear like it could almost stall or something and surging a bit at cruising speed at around 5-6k. popping/burbling on decel. some slight backfire if backing right off at higher speeds and going back down through the gears even giving it a liitle rev going back down gears.

anyone got theirs just right for these mods with these jets using the dj main and needle and keihin pilot with these mods.

someones got close specs but not sure of jet brands and not exact exhaust specs but close.its the little things that make the fine tuning a pita taking the carb out getting really sick of it ..

[matt3357]

Try going to a 38 pilot, 40 with 2-3 turns out sounds too rich.

I'd try 1 turn out and see how it goes first though.