kx250 jetting database 05-07

Looking through chickenhauler's faq, it seemed like the 250's were left out, so I'll start this. Stuff that might be helpful:

  • altitude and temps where you ride
  • riding style (pokey lugging woods rider, revving desert fanatic, mx racer, etc..)
  • aftermarket pipe and/or silencer
  • main, needle, needle clip, pilot, air screw settings
  • spooginess, with mix ratio and oil brand

I've only got 8 hrs or so on the bike. I'm currently at

160 main

nftg (stock needle) clip#1

42 pilot

1.5 as

riding, lugging in the woods at 4000-6000', and 30-70 degrees the bike runs very well at the upper end of that range, and has a little 'kak-kak-kak' feel to it at small throttle openings, middle revs in the deepest coldest canyons. I think perhaps the needle is slightly lean there.

spooge is minimal from back of pipe, but messy from the pv vent, running 32-1 maxima. Next tank I'll be switching to my normal amsoil dominator at 40-1 and I'll do further testing. Based on my lugging riding style, I may try a hotter plug. At least 1 other poster in here reported going to a br7 worked for him to de-spooge in woods conditions.

Anyone think I can drop that main further? esp if I go back to clip #2 on the needle?

Can't help with the 05-07 but on my 99-02 they like 152s at 5000' and needle in #2 with 45 pilots. I say try it in the mountains but go back to the 160 in the desert until you learn what it likes. Good luck

Ed

Between 500' and 1500' here in Ohio. I've been running 32:1 Yamalube. 42 pilot with the stock pipe, 160 main seems good. I run Citgo 110 octane gas. JD jetting red needle 2nd or 3rd notch. Had to go to a 40 pilot when I installed an FMF Fatty was spooging badly! Spooges a little bit now. I ride trails aggressively and tracks not so aggressively!

llamaface at your elevation I'm sure you could go leaner on the main if you need to.

'06 KX250

Engine is all stock except for Platinum 2 pipe and TC2 silencer.

3000' to 6000'

Southern California, High Desert

168 main

Red JD needle

3rd Position

42 Pilot

1.5 Air Screw

100LL AV Gas

32:1 Klotz Benol

Anyone think I can drop that main further? esp if I go back to clip #2 on the needle?

In theory, yes because you'd be richening the circuit from at least 1/4 to 3/4 throttle openings. If you're not past 3/4 throttle too often then this should hold well. Keep in mind that 32:1 is leaner than 40:1 because there's less overall fuel available at that ratio. So, a smaller main combined with 40:1 (to compensate perhaps) may do the job.:worthy:

You describe a kak-kak-kak from just off idle, occasionally at half throttle, and sometimes in the coldest canyons you ride. Me thinks your pilot and needle are both a hair rich combined with some AS dialing. If you're at clip position one now and go to #2 then you'd be richening that. Perhaps a 1/2 step overall leaner needle instead on #2 to start and then put it on #1 if it's still too rich (indicated by stutter or hesitation). In this case, I'd stick with 32:1 if you got a leaner needle cause the extra oil makes me sleep better at night. :eek:

160 main

nftg (stock needle) clip#1

42 pilot

1.5 as

Okeedokee. I have a little more time on the bike. ed (no1clyde) gave me a NAFF needle when he was up here. I tried it on #2, and it was better than the nftg at clip 2, but after another couple rides, I went to clip #1. The NAFF doesn't have any of the weird semi-lean-sounding behavior, and no pipe-bang on decel or anything else alarming. It seems a little weird to be on clip 1, but otherwise the bike is pretty well-behaved. If anything, it might still be a smidgen rich at idle or just off. Just a teensy amount of spooge from the pipe. Did a plug chop and the plug looked fine.

So now I'm at:

160 main

NAFF clip #1

42 pilot

1.5 AS

for 2500-4000', 45-55 degrees.

If I get bored next weekend I might try some single-taper needles to see if that cleans up the very slight sputter just off idle. Or I might just ride faster.

Good to hear it is working for you. Thursday I am going to Yerington and will hit Wilson Canyon and think you guys need to come on one of these rides someday. I think I wil take the 250 for that ride too, as it was working real well up there in Idaho. Have fun.

Ed

If I get bored next weekend I might try some single-taper needles to see if that cleans up the very slight sputter just off idle. Or I might just ride faster.

Why not the next down leaner pilot combined with a 0.75-1.0 on the AS instead? Is your exhaust stock? Aftermarket usually makes it richer.

dont make a generation specific thread, make it all kx250's.

Why not the next down leaner pilot combined with a 0.75-1.0 on the AS instead? Is your exhaust stock? Aftermarket usually makes it richer.

I might try a 40 pilot too. stock pipe, fmf q silencer.

I lug alot, and ride alot of fairly low-speed terrain so even a bike some people think is jetted well can be annoying for me. For example, on ktm 2-strokes, i have found there are no settings i'm happy with using the stock nozX series needles (unless i'm racing in sand, then they rock). But with a DDK or CCL or similar single-taper needle, I can clean up the small throttle openings.

I have no idea what the measurements on the nftg or the naff are, but they feel somewhat similar to the noz needles in that they work better the more aggressive you are and the faster you roll on the throttle, but the seem to have a little bit of sputter if you roll on a bit slower. Dunno if that makes sense. I'm probably just spoiled because my 200xcw carburetes very clean and smooth with zero sputter down to about no rpms at all and tiny throttle openings. I don't really have alot to complain about with the kx, but I can't help but tinker and experiment.

Hey Ed, I spent most of the 4-day vets weekend exploring and refreshing my memory with cool desert trails. I found a crapload of killer singletrack, pretty much like the best stuff we rode when you were up here, only more of it, and better. :worthy:

in fact...I rode woods and I use NOZF (ex Ktm...) needle at 2#, 40-168

stock NFTG seems to be lean in midrange

NFTG taper is 2.715mm and NOZF is 2.705mm

kx250 05 stock with torque spacer.

50:1 Motul 800, 95/98octane gas

Zac

I might try a 40 pilot too. stock pipe, fmf q silencer.

I lug alot, and ride alot of fairly low-speed terrain so even a bike some people think is jetted well can be annoying for me. For example, on ktm 2-strokes, i have found there are no settings i'm happy with using the stock nozX series needles (unless i'm racing in sand, then they rock). But with a DDK or CCL or similar single-taper needle, I can clean up the small throttle openings.

I'm the same way. I'm quite picky about any stutter or bog I get and must attack it until it's fixed. I've got a stock pipe and a FMF TC2. I'm three full needles leaner, one main leaner, and two PJ leaner in the summer. Come fall, winter, or spring here I just fatten up the PJ by two and I'm good. I actually want to just fatten by one as there's just a slight cackle below 1,000 RPM now.:worthy:

However, this is on a blue bike so what the hell do I know.:eek:

Thats great Mark, may be in a few weeks I'll make another trip up and let you show me. If the weather is good after Thanksgiving I should have some time. I need to do some work to my 310 but it will need to be tested about then,LOL.

Ed

155 main

stock needle on clip 1

45 pilot

1K-3K feet eleveation 40-50F degrees

110 octane 32:1 927

I have searched everywhere and cannot find a good chart that lists the available jetting for the Keihin PWK38S. Does anyone know where I can find it?

I'm also trying to find a #42 pilot and NAFF needle and it seems Kawi's fiche only goes down to a #45 pilot and doesn't list the NAFF. Who is a good source?

Forgot to say: I foul plugs when following my 9 year old around and when I ride with "the big dogs" my plug is chocholate brown and doesn't foul.

You should be able to find the 42 pilot at Dennis Kirk or try carb parts warehouse,that's where I get all my jets, they are local to me.

I'm also trying to find a #42 pilot and NAFF needle and it seems Kawi's fiche only goes down to a #45 pilot and doesn't list the NAFF. Who is a good source?

Check these guys. They go down to a 38 PJ.

Check these guys. They go down to a 38 PJ.

Thanks! Now to find a source for the NAFF.

Order the NAFF from Kawasaki. Look at Kawasaki.com at the parts list for the 01 or 02 KX250 to get the part#. You can also order the next leaner one there too, I think it would be the streight section that would be the leaner part and my be what Llama needs.

Ed

Finally! I putted around behind my son yesterday for four hours and didn't foul a plug. And that was after three heat cycles on the new top end with the same plug.

155 main

NAFF - clip on the second position

42 pilot

1.75 turns on the air screw

Gnarly pipe with Q silencer

110 octane with 927 mix at 32:1

35 degrees at 1500 feet elevation

Thanks to everyone for the advice! :bonk:

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