Carburetor jetting for 2 stroke dirt bike using JD Jetting kit - KTM 250 SX
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- Опубликовано: 5 фев 2025
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How to jet your carburetor on a dirt bike using JD jetting kit. What is important to know about the jetting and carburetor to get the most out of your dirt bike.
Find out more about the kit: www.jdjetting.com
/ dirtniron
Today this video is 5 years old and it's still relevant. Thanks Rado!
thanks bro, glad it helps!
I own a 2018 beta 250rr and I used this kit. What a difference! It runs amazing now ! It always ran boggy and would not idle well. No more .Thanks for the tip 👍
Thanks for sharing
@@dirtniron hi.. thanks for sharing your knowledge with us in here... I follow your tips always... I bought the JD jetting kit after I saw your comparison with your lectron carb... I have a YZ250 01' and when I bought it the guy told me that bogs a little bit in open throttle... so I check the float and was to low and when I check the main jet was a #192 pilot #50... from factory it said 50 and 178.. my question... JD jetting kit for my application recomends #45 and #172 red needle #3 ... do you think It would be safe running smaller than factory? The throttle response is crisp but I feel that in open throttle needs a little bit more... should I play with the needle or go up one size with the main jet? Thanks
I just put jd jetting kit on my 94 kx 125 and again works perfectly 👌.
I just did the same on my 17 250rr. Amazing 👌
I just used it for my 89 Cr 125 and I also bought it for my my 2014 Drz 400 sm
Very easy and clear explanation of the basics of carburetor jetting. I was trying to explain this to a guy at work but it was way easier to send him this link. Thank you for sharing.
Cool bro, glad it helps!
Thank you for this! You made understanding carbs so much easier!
Happy to help!
I put a small, flat magnet in my butt bag to help me on the trail when changing needle clip. Doing it with needle nose pliers, I dropped the clip in the dirt and looked for it for 30 minutes. Now, I just press clip against magnet to release it, the magnet grabs it, and I can change position by pressing it fully into slot with the magnet.....no way to lose the clip. Works for me.....
Thats a cool trick, thanks for sharing Tom!
I don't know how I missed that video! great video. Already contacted JD to see if they have a kit for my GG EC125 '14.
1st gear idling and it's not dying - THAT'S A MIRACLE FOR ME! LOL
they have list on the website, I dont see 125cc though, hope they will update it soon, good stuff!
I'll let you know, they asked me to picture my carb and send them. I hope they have a kit for me :)
Hey Rado, last week I picked up a sweet 2016 TE250, the engine is in stock condition but sale came with an unused JD Jetting kit. I've been riding EFi bikes for awhile and am now educating myself on dirt bike carbs. This is great information, thanks a ton. I'm going to take a couple rides on the stock jetting to get a baseline, then switch to the JD kit.
Best explanation of jetting that I have heard. Great video.
thanks, glad it helps!
Cold front moved into central cal this week with rain and high humidity. On my yz 125 today and it ran like crap. I quit early , disgusted. I think it’s the temp and the humidity. Great video.
you need to give her little more fuel, try turning air screw in
Dirt N Iron It has a really wet spark plug. Wet with oil and gas. I’m assuming the heavy humidity is causing the choppy acceleration. Thank you again.
good video, just skip to the 7:00 mark when he actually starts doing some work
Thankyou. Great video. Great JD kit too for $ 80
The main jet affects the idle too, depending on how low your needle is sitting i think. I had problems with uneven idle, and dies when giving it gas. Never touched the idle jet, but putting in a much larger main jet solved that idle and gas response issues.. But now it gets too much at high rpms (feels like rpm block and plug is a bit wet)
I would not adjust the idle with the main jet, did you try different pilots and needles ?
@@dirtniron I ended up moving the needle one step higher, and put in a slightly smaller main jet. Now it is usable, quite strong and responsive. Sometimes it would also have no response at all between 1/4 and 3/4 gas, not bogging or drowning, just "quiet". But putting in a slightly smaller main jet fixed that too. This is a heavily modified moped by the way, so I have to figure everything out myself :)
I have the same issue with my YZ250.
Another option on 2 stroke dirt bikes is to replace the stock carb with a APT smart carb ( very similar to a Lectron carb ) about $400.00 / billet version $700.00 It has no pilot jet, needle or main jet to deal with. No more jetting issues, ever! There's a metering rod inside attached to a lean / rich knob on the top of the carb to adjust how lean or rich the fuel mixture you want. It also adjusts the engines idle. It has a air screw to make fine tune idle adjustments. The smart carb also adjusts for elevation, better gas mileage, runs super clean throughout the power range, it's like fuel injection for a 2 stroke. Under hard decelerating from speed there is no more "ding-ding" sound coming from the motor. It works great, never going back to a regular carb.
that sounds interesting, I would love to try one of those carbs
Love your videos.
I run a tmx38 mikuni. Air screw is two turns out. Very crisp and responsive however just won't idle. The idle screw is all the way in. What could this be and what remedy we would you try?
This video will come in handy. I want to get a Yamaha 2014 250 2 stroke. all I have right know is a 125 4 stroke and a 250 4 stroke.
thats a great bike, 2014 yz250 is a beast you gonna have a lot fun on that bike!
Confusing... Leaner at San Diego or at altitude at home. What number jets are these?
Yea I thought so. I dropped needle and set the float. Started easier but idle screw is all the way in . Thought maybe it was mostly float that made it easier to start. An I to go other way with needle.
try to bring the screw out 1-2 turns
Love your vids...professional and on point. Keep up the great work !!. subbed for sure !!
thanks man, welcome on board!
So if reference to the fuel air ratio is the only appropriate application of the lean/rich terminology how do we describe the way am engine is running when there is less oil in the gasoline and I assume here- more combustion- the same way less efficient combustion results when oil is too heavy.. these seem like rich and lean traits to me.. maybe all 4 are factors of rich and lean conditions and it doesn't have to be 1 just way of the other?
Great video. Again. Subscribed!
cool man, welcome on board!
Which spring in a power valve? Red Yellow Green?
stock one, whatever color that is.. I didnt change it
@@dirtniron yellow is stock
that thing is a beast!!
yea, it runs pretty well, specially once jetted right!
Thank you for your time..good job
thanks Ray ;)
where to buy this carburetor?
Hay dirt I been fouling plugs since I bought the bike brand new ktm 2 stroke 2016 . I followed the manual for carby settings for tem and altitude starts great but after 1/8 it bogs down and fuel and oil mixture in manual as followed
+Justin Wellbelove try to drop needle down one cut. Sounds like you are little rich on your pilot circuit. See what the needle does. If you have different needle from factory, check if it's leaner needle and replace it. Also play with the air screw a bit and see if it clears out. You need to get her more air, so air screw needs to come out little bit. But keep in mind air screw is just fine tuning. Main things here are pilot jet and needle. Let's me know how it goes
Nice video! Thanks!
+Dave Cushing cool bro, thanks for comment!
Hello! Awesome video!!
JD kit isnt easy to get in europe..... even harder in Portugal...
Question: I have the Keihin PWKS 38 ( 2013 GasGas EC300) but i can´t find a chart (temperature/altitude) like the ones of the Keihin PWKS 36 (easy to find on ktm or husqvarna website/manual for example). Can we use the jetting of the 36 for the 38 has a starting point?! And then do some tweaks on airscrew or needle clip maybe?
compare 38 stock vs 36 stock and then see how it changes with elevation on the chart for 36 and then take the same changes and apply it to 38. Thats how I would do it I guess. Its always safe to use stock jetting as a starting point and then play with it.
Love your videos! I have a 2004 ktm 125exc and have replaced almost everything and it wont start. I have spark, i have fuel, i have compression. Wish you had a repair shop
its hard to say what could it be, try brand new spark plug and make sure your pilot circuit is clean.
Dirt N Iron i have replaced the plugs 6 times, got new fuel twice, has new piston with 2 rings, new gaskets, power valve is set at 42 1/2 like oem, carb has been rebuilt and cleaned, new ignition coil, new plug wire, new stater and clocked it right. Has 185 and 45 and 2nd notch from the top.
The only thing left is the cdi but im getting spark so it cant be cdi right?
Dirt N Iron well i got it running. I tryed a higher heat range plug the br8es.
Just to make sure i put back the br9es and it wouldnt start put the br8es back in and it started first kick
Great vid man definitely got me going in the right direction 🤘🏼✊🏼💨💨
cool man, I am glad it helps!
Dirt N Iron Quick question so when you drop pilot jet size do you need to adjust the needle also to give more fuel
it depends, if the bike runs good then no, if you want to fine tune then yes
Dirt N Iron It runs a lot better but after a while of on and off throttle on a single trail It seems to surge when idling my needle is at 2nd click from the top I was thinking of putting it in the middle
try, you can always put it back
I have a KX125 2007 bike has 5 or 6 rides on it and I’ve fouled multiple plugs, the plugs are black and oily I’m also running main jet 420 pilot jet 40 and clip position 3rd. I’m using a br9 es plug. Bike runs great until the plug is Fowled.
you are bit rich, try to adjust air screw, play with needle or maybe even re-jet
Dirt N Iron I just ordered a Jd kit for my kx125 2007 and it says to run blue needle on position 3 and change my 420 jet to a 430 for my elevation. I’m already running rich tho?
follow first what they say, ride it and see if you need to adjust a bit
Did you fill Big difference betwen the original jet and the throttle and this set ?
Yes, bike runs better i can feel feel it. Crisp and responsive. It depends how good is your jetting right now, if it is off then you will feel a big improvement
i just bought a new yz 85 but I know nothing about dirtbikes so what should I do before and after each ride ?
Check my maintenance videos for beginners, there is playlist on my channel
ktm 380 hard to start would that b pilot jet?
+nick hunt it can, also try to play with air screw, needle position
Spark plug
I Need Help
I made it how you said but now it keeps
running gasolin out of a overfill pipe?? 😓😓
Why could this happen its this pipe on the bottom of the carburator, there where you changed the main jet and pilot but not out of the screw out of this pipe hanging down??
My english is not the best but pls can you tell me what could be the problem?
looks like your float valve is not closing all the way, its either worn out valve or the float height is not adjusted correctly. That means that gasoline flow from the tank is not shutting down, thats why you have overflow.
Dirt N Iron
Thank you very much for your answer, it was dirt on the float valve thats why it didnt closed completly, i cleaned it and its working now😎
THX 👍
thats great man, I am glad its OK now. Take care
Dude the jd jetting kit says nothing about temperature, so in colder weather how do we tune? The kit only comes with one pilot jet
two needles, one is for warm and one for cold weather, there should be explanation on the sheet
On my JD kit temperature is not mentioned, just needle color and position and jets for altitude range.
yes, thats right, one needle is for lean and one for rich conditions, in hot weather you need to make it leaner and in cold you need to make it richer thats pretty much the basic guidance for temperature.
Dirt N Iron blue=cold, red=hot ?
i think so
Great video!
+CoC ELITE thanks man!
Hi , nice video ! My question is what premix ratio that you use ? , me I have 2019 yz250x whit Jd , I'm testing my jetting , and I will be testing the amsoil dominator and motul 800 , and I would want to know if you run 50:1
Nice channel By the way I like your vids !! 🤘🤘
I run 50:1 on my KTM
Bro. 50:1 is way too lean. I run 32:1 but 40:1 may also work. 50:1 is not enough lubrication for your piston.
@@marioguzman9290 yeah thanks men , I sell my bike but finally I ran 40:1 motul 800 with jd setting , and wow awsowme result , brown tan color on the spark and brown dark in the rick setting of the jd setting and wow the jd needle was aswome
Rich
I'm trying to look for a JD jet kit for an older yz 125
go for it, they should have kit for your bike
my bike starts dying in first gear while riding in a hard terrain forrest. should i get one size bigger pilot jet and try if it works?
I am not sure, try to address gearing as well, maybe first play with air screw too. Check my air screw adjustment video.
thanks man you are the best motorcycle youtuber! i love your tutorials.
Hey bro, can't I rely on my manual specs?
I need some help I'm about to put a new top end on my rm 125 and they say to run it rich for brake in, I run 40:1 without a prob at all. Should I re jet and run richer for brake in or mix a little bit extra oil when I mix the gas ?
i would go one size bigger on main jet, one size bigger on pilot and do 32:1, if I remember correctly thats what suzuki recommends. break it in, then check the spark plug, see how the bike feels and jet it correctly. if you go little richer its safe, you are getting more lubrication and more cooling as well.. (more fuel = more cooling) good luck Isaiah
What would happen if I mix 32:1 without jetting the carb would that be fine for break in and then run 40:1
+Dirt N Iron keep 32:1
Alright and thanks for the help
I've got my bike re built and it runs great on 32:1 and I've done a little research about what it means to run lean and what it means to run rich. To run rich it means your running to much gas and less oil and to run lean is more oil and less gas.
Hey man what would you do if the previous owner put a 52 pilot jet in and it smoked alot and fouled a plug but was able to hold idle fine. I put a stock 50 in today and it leaned it out a bit but I can back the air screw all the way out and makes no difference. If I run it all the way in it dies. Keihin pwk38s-ag on an 03 ktm 250sx fmf narly pipe and q stealth silencer
Try to keep 52 and set your air screw better. What mixture ratio do you run? I have pretty much the same bike and i run 50:1
I run 40:1 premix.
Will try 50:1 this weekend and see what it does
I saw on JD jetts website that they have jetts for 125sx, but are these jetts good on my 125 exc? Because on the website they don'y have it for the 125 exc model
make sure those bikes has same carburetors, some offroad models had different size carburetor so the jets would be different too.
@@dirtniron ok thanks :)
Oil does matter, IF u have alot oil in ur fuel your engine is getting less fuel bc IT gets more oil instead. So ur Bike Will run lean IF u put in more oil than the Bike is tuned for
Elias Emanuelsson the guy in the video needs to prove his point and run straight oil, without gas, in his bike "tuned" with his "fuel:air" ratio.
He lost all credibility right from the start.
32:1 on my YZ250
Hi my 2001 Suzuki rm125 doesn’t idle without messing with the throttle cable and it Boggs from 0-1/4 throttle. I live in California and ride yearly. Any pilot jet and needle suggestions? Needle is on the all the was top
I am not sure, I would first determine if it's rich or lean and try to move one way. See how it responds. Check my video how to set idle on 2 stroke dirt bike
Dirt N Iron I checked that video out before and it still doesn’t idle correctly and at my first race the announcers said my bike is running rich. I don’t know nothing about running rich or lean.
The JD Kit and what oil to gas ratio?
50:1 on trail riding KTM
hey man i looked on JDjetting store and found a kit designed for my bike. but there are only main jets and needles (with needle clip). But i cant see there any pilot jet and i think that i need to change my pilot jet because it is too rich and do not response even that i set the air screw correctly. why is there no pilot jet?
if there is no pilot its because they tested it and got the best results with stock pilot, their needle makes the difference. try it out first, if you really have to drop pilot size, you can buy them separately for few $. First follow 100% the instruction, it worked for me in the past. Hope that helps! good luck
thanks man!
What gearing do you have on your 250sx
13-50 i believe its stock also tried 13-49 and was ok too
You ae amazing!
Would they have a kit for a kx 85 or a yz 85
here is one for yz
www.jdjetting.com/xcart5/jdy017-yamaha-yz85-02-16-.html?category_id=55
I just got an 04 cr85r and it’s fouled 2 plugs so far in like 2 weeks. Not sure if it’s Jetting or bad shifting. It’s my first two stroke as well. Any tips?
make sure you are not too rich, dont use too much oil when you mix and when you ride, hit high rpm as well, those engines like to be "singing"
check your mix ratio and make sure you dont use more than what is recommended. good luck!
Dirt N Iron Ok thanks for the help!
I get a knocking detonation sound when I decelerate 2017 beta 300 2T with JD kit ,what part should I adjust thanks
sounds like you are bit lean, adjust the air screw inward or if its really bad then adjust the needle clip position one clip richer
Help! Hello, I just a 2002 mxc200 took it for my first ride, at altitudes of 1600ft to 4000ft it ran pretty bad first it didn’t want to start, when I was I was coming back down it wouldn’t stay idling and the worst part it waisted a f 3 gal tank on about 1hr 30m ride? Any help would be appreciated
Sounds too rich, you need to jet it. Make sure your reeds are in good condition too
Do you know where the fuel screw should be at? I have it at 1and 3/4 turn out counter clockwise? I will check the reed valves, how would that affect my bike? It’s my first 2stroke bike so I’m a rookie on them. Thanks for all your help I will follow ur instructions on rebuilding my carburetor
The screw is just fine tuning for iddle and first throttle response. I think bad reeds cause your bike to lose power and run rich. It's good to be sure that they are good. It's like a check valve, if there are cracks or they don't seal well engine won't run well and I think it's impossible to jet it right. Those are the things I would check.
I will do that thank you for your help
how did you know to lift the needle clip one the make it a little richer
it was cold outside, and I felt that bike is little lean
Dirt N Iron thanks btw your may favorite Moto channel
thanks Aaron, appreciate it! ;)
What kit is that ? Where can I buy it ??
+Angel Garcia it's called JD jetting kit, you can go on their website jdjetting.com and search for your bike model and year, they will have specific kit for your bike. It includes main jets, pilot jet and 2 needles. You can also search eBay or any other online dirt bike store.
Bring on da smokers
I bought the oem jets I needed for 16 instead of 80
jd has very good needle..
Hi i have a 97- kx500 from new first problem after about ten rides went to some big hill climbs long deep sand bean canyon 500 to 700 ft long . First 300ft 4th gear to 3td gear full throttle in the next 100ft cuts out roll of throttle lights back up it was running out of fuel . My friend had a 96 kx500 same thing he lent it to girl friend brother moto crosser he did some carb work it never did it again . On my 97 kx500 changed pipe FMF fatty pipe and jetting same problem runs out of fuel after like 5 - 8 seconds WOT. hill climb .. some of these kx500's did this there's a stop so you can adjust the float droop i guess for track riding to keep fuel from over flowing in turns an woops it limits how much fuel will get buy the needle jet so for you hill climbers its some thing to check . I have not rode in 7 years due to a fussed right wrist i might try again this winter if it still falls on it's face and i ride again it will get dynode. good video . JM
good luck man! thanks for sharing
@@dirtniron is there a way to show a photo
The subtitles 😂
for yz250 1996?
Check their website
Dirt N Iron sorry again..products can be sent to italy?if yes,requires a higher charge?
Can somebody please please help me man I have no idea what all this jetting stuff is talking about I've been riding motorcycles since a little kid four wheelers you know dirt bikes I just never ever got into the whole do this do that to your bike I always just got a dirt bike and rode it how it was that's what it was to me. Now I got this 1990 Yamaha YZ80 I'm 31 years old I got it just to play around with when I got the bike nothing was on it nothing at all everything was stock I went and bought pro taper handlebars I'm doing the bike all up it's looking real good and I want to start doing all these mods to it I've bought boyson reeds cuz that was the first thing that I thought I could be able to do on my own and sure enough I was able to put those in and the bike runs way way better a lot faster on the acceleration and people are telling me that I had the jet it once I put those on and even the directions is saying that I had to mess around with the main jet the pilot yet all those things that I have no clue of but as I said I put those in and start at the bike up and wrote it and it was fine to me I had a lot more tweak to it and more response when you blip the throttle so I just left it alone I figured it didn't have to be done but obviously there's directions for something right now I'm not going to mess with it cuz nothing's wrong with it and it's a lot more progress from putting them on without me having to do anything can somebody explain or did I really not even have to do all that stuff because my bike reacted to it just fine
Iv got a ktm 125 sx 2013
Just had new piston and rings and spark plug, took it to the track and it was bogging bad in 2nd gear but fine after that any suggestions ? Thanks
where is the bog? on the bottom? I would go with bigger pilot if thats the case, or at least adjust the air screw and get her more fuel. It could be lean on the bottom
@@dirtniron yeah on the bottom mate, I'm not to clued up on jetting and stuff but I'll give the air screw a try thanks
Also thanks for the reply,
Looking at getting one of the jd jetting kits as well in the next few weeks
hey man great video, just please stop engine braking to slow down!!
thannks Sergey, but trust me.. 2 stroke engine braking wont hurt your engine.
Dirt N Iron oh? I thought it blocks off the air and fuel mixture and ruins your engine. And Please help me out, I have a 2002 Kx250 and there is a very faint rattle noise, I read it might have something to do with a lean air/fuel mixture. It sounds like a very faint metal rattle kinda like my pipe is shaking or the kicker is hitting the pipe. Please help out!!
@@dirtniron This seems to be a new thing going around where all these people are saying how they blew up there motors engine braking, I have been riding 2 strokes since the 70,s and I have never blown an engine and I engine brake all the time!!
You look really high 🤨😂
i dont get high.. not that kind of guy
Two stroke guys usually have that look because they get high off of the exhaust fumes.
Hello I have a 2010 yz 250 two stroke. The JD jetting kit is the same if I want the bike to motocross (track) or enduro (trails) ?
Big thanks.
Yes, its the same.
@@dirtniron do they sell different kits for cold and warm weather?
Or a tc 85
here is for husky
www.jdjetting.com/xcart5/jdhq20-tc85.html?category_id=59
My bike is running good but at full throttle there’s lots of smoke I run 32:1
It’s a YZ125 btw
It doesn’t foul plugs but they are very wet
I would say try to drop one size on main, but make sure its not getting too lean, its better to be hair richer I think..
Dirt N Iron thanks man
Please help. I have the needle on position 5, super rich, that’s how my kart runs best. Should I change the pilot jet to a bigger one and bring the needle down to position 3 or 4? My understanding is that if the needle is in position 5 or 1, you should change the pilot jet accordingly so the needle stays in position 3. Please suggest, thanks
you can but if it runs great now then maybe just keep it
Dirt N Iron
Makes sense, but “maybe it can even faster” that’s the question. Thanks 🙏
Idle is to high ! Your bike 🤷🏼♂️