How to know if the bike is running lean?

[Munch]

You've been given much advice munch. No one will really be able to recommend you a needle because you haven't confirmed any details such as:

Model of carb (AS1 or 2) - Suspect AS1 given its an 06 250.
Slide number (and if it has a notch cut in it).
Have you set the float height? The magic number depends on the model of carb. See above.
The fuel overflow issue - have you determined if it is the float height or the Viton tipped needle valve? You won't have success if the engine is intermittently flooding itself.
Your temperature, elevation, fuel quality (RON?, ethanol blend, etc).
Mechanical history? Have you taken any comp readings? Done any leak down tests? You won't be able to jet around a mechanical issue.
Which leads us to squish clearance too. You can spend a lot of time jetting in circles if the head to piston clearance is excessive (as some stock setups have been).

And after all that, Capz gave you some advice back on page 1 "I used to run a 45pj and 180 main with one of the N3 series"

That's where I would start too. 45 N3EG#3 180 probably.. depending a whole lot on the answer to the multiple questions above.

KTM part number: 54731134000 ..available through whichever source you please, at probably a load of difference price points.

Main point to note is that it is the whole package working together. The whole carb needs to be in good order. The whole engine too. Be methodical and precise in how you approach it, and you'll end up gaining a wealth of knowledge and a bike that runs just the way you want it to.

You've been given much advice munch. No one will really be able to recommend you a needle because you haven't confirmed any details such as:

Yes I am very greatful for the advice I have been given and I also thought I had given a lot of the info, I am new to the whole jetting thing and a bit bummed out I bought a bike that I can't get running correct, sorry if I come across as rude.

Model of carb (AS1 or 2) - Suspect AS1 given its an 06 250.

The carb is AS1

Slide number (and if it has a notch cut in it).

By slide do you mean the needle? It is set to #3

Have you set the float height? The magic number depends on the model of carb. See above.

Not yet, I will do it before trying anything else though. I was asking about the JD kit as I was looking to collect a few jets/needles ready for when I spend a day trying to jet it correctly.

Your temperature, elevation, fuel quality (RON?, ethanol blend, etc).

Temperature is around the 60-70F mark as it's approaching summer here in the UK. 0-1000ft, fuel quality is 95 I think.

Mechanical history? Have you taken any comp readings? Done any leak down tests? You won't be able to jet around a mechanical issue.

I bought my first bike (kx 125) around 18 months ago and quickly realized I prefered trail riding/enduro type of riding, while owning the kx I did a top end and a bearing in the gearbox went so I split the cases and put fresh bearings in the bottom end myself.

Which leads us to squish clearance too. You can spend a lot of time jetting in circles if the head to piston clearance is excessive (as some stock setups have been).

This is all new to me and I have no idea what a squish clearance is, I guess more reading for me!

And after all that, Capz gave you some advice back on page 1 "I used to run a 45pj and 180 main with one of the N3 series"

Yesterday I went out and put the 180 main in and had the 42pilot in and the bottom end was fine as always but the top seemed even worse than the 172, I tried 178 but problem was still there. I rode for approx 30min, had a 10min break and when I got back on the bike it was 10x worse, I don't know what caused it but I ended up stopping for the day. Based on the videos I had been shown in the thread the past few days the bike was 100% running lean as when I would WOT it would make the similar noise to the KTM video, I stopped because I was afraid of heat seizing the engine.

That's where I would start too. 45 N3EG#3 180 probably.. depending a whole lot on the answer to the multiple questions above.

I have just ordered the N3EG needle and a 45 pilot jet, I have just sent off my shock for a service so will probably be the weekend the next time I get some testing done.

 

[Capz85]

It's alot to take in and trying to make progress with jetting can be annoying when your trying to figure out what exactly your looking for, but keep at it and keep making adjustments and eventually you will get somewhere, like they say they can't just say these are the settings you want as what works for one might not work for another but we can put you somewhere close providing the engine is working as it should

I think you will like that N3EG you've ordered, I was happiest with this one

Where abouts in the uk are you?

 

[Munch]

It's alot to take in and trying to make progress with jetting can be annoying when your trying to figure out what exactly your looking for, but keep at it and keep making adjustments and eventually you will get somewhere, like they say they can't just say these are the settings you want as what works for one might not work for another but we can put you somewhere close providing the engine is working as it should

I think you will like that N3EG you've ordered, I was happiest with this one

Where abouts in the uk are you?

I am in South Wales mate how about yourself?


When I removed my shock ready for service I decided to set the float level, I took the carb off the bike and took off the bottom cover and I think I found the reason the bike performed so bad towards the end of my last ride, the main jet had come out of it's place.

Video of float: https://www.youtube.com/watch?v=M5kI-KJToBw to me when I tilted it the float seemed to be in the correct place? What do you guys think.

 

[Capz85]

At least you have some good places to ride round there, I'm in the West Midlands nothing here unless you want to ride mx tracks

 

[Jakobi]

No worries Munch. Sorry if I came across as rude too. I've also been in the same place with no knowledge at all, so can appreciate what it's like trying to take on all the information and process it all, and then implement it.

My steep curve came with buying a brand new, out of the crate, 2010 model. Every model since forever has come with a standard needle that leaves room for a lot of improvement. It's not all that different with most brands of bikes either.

The slides themselves (the part that holds the needle) can be cut at varying angles. They will have a number stamped into the bottom of them. It is another tuning variable.

In terms of mechanical history, I was address the bike itself, rather than your personal ability. The point being that if you have a stator side seal that is failing and causing your bike to lean out on you, then no amount of jetting is going to improve the condition - it is a mechanical problem; not jetting.

Disregard the squish for now.

Strange that you describe lean conditions occurring, however adding larger jets didn't improve the situation.

Needs to start with the float though, then adjust the needle as it covers the largest range of throttle. Get off idle and pilot dialled, and finally bring the main down to where it runs best. Methodical!

 

[Munch]

No worries Munch. Sorry if I came across as rude too. I've also been in the same place with no knowledge at all, so can appreciate what it's like trying to take on all the information and process it all, and then implement it.

My steep curve came with buying a brand new, out of the crate, 2010 model. Every model since forever has come with a standard needle that leaves room for a lot of improvement. It's not all that different with most brands of bikes either.

The slides themselves (the part that holds the needle) can be cut at varying angles. They will have a number stamped into the bottom of them. It is another tuning variable.

In terms of mechanical history, I was address the bike itself, rather than your personal ability. The point being that if you have a stator side seal that is failing and causing your bike to lean out on you, then no amount of jetting is going to improve the condition - it is a mechanical problem; not jetting.

Disregard the squish for now.

Strange that you describe lean conditions occurring, however adding larger jets didn't improve the situation.

Needs to start with the float though, then adjust the needle as it covers the largest range of throttle. Get off idle and pilot dialled, and finally bring the main down to where it runs best. Methodical!

Not sure if you missed my post above where I showed a video of my float but if you could check the vid and give me your opinion that would be great.

Also I think the lean condition could have been because my main jet fell out lol.

 

[Jacob 'Berg]

Not sure if you missed my post above where I showed a video of my float but if you could check the vid and give me your opinion that would be great.

Also I think the lean condition could have been because my main jet fell out lol.

Seems like you would be getting too much fuel without the main jet.

 

[Munch]

Seems like you would be getting too much fuel without the main jet.

Would the main jet coming out cause this noise https://youtu.be/zVzqqpgviyI?t=237 (go to 3:57) to happen at WOT? it revved ok through the range right up until the main jet would usually kick in then I would get that noise and no power so I stopped as I was informed this is what lean sounds like.

 

[GGRider01]

Eh, you dump enough fuel into the motor and it will die and sound just like a lean bog even though it's running rich. Get the main jet snug, but be careful.. it is brass after all.

 

[Capz85]

http://www.smellofdeath.com/lloydy/jetting.htm

Have a read of this

 

[gasman88]

The plug has some use,but the key is its relative to how the bike was ridden last/rider style.a lot of puttering will darken,look rich/a wot run right before pulling plug will show a greyer/hot/drier leaner looking plug.
Pay attention to where the problem areas are-pilot=0-1/8 with a small affect to 1/4.main=3/4 to wot.needle type/clip=everything in between.
With that needle the best youl likely get is ok 0-1/8,blubber 1/8-1/4,then whack,clean mid hit to wot.
The blubber just before the hit makes it difficult in tight technical stuff.if you ride wot/fast the mid to top hit is fine,but when you roll on/off it may burble then hit.changing needle type will help get a smoother transition

Sorry for bring up an old post but that is dead on how my bike runs. From idle to maybe 1/4 throttle it blubbers a little. It gas gotten better after I put the clip on the very top clip position and put a 40 pilot in it compared to the 45 that was in it. It used to do it in first in second. Now it's mainly first. I looked tonight and it does have the n1ef needle and number 7 slide. Anything past 1/4 throttle she runs like a raped ape. That blubber is very annoying to me though, and can't have it in the woods where I need power. It was about 55 degrees outside today and I'm at about 200 ft above sea level. 180 main, 40 pilot, air screw seems best around 2 1/2 turns out, n1ef needle at leanest setting. Idle screw is way far in which tells me something is not right. Cleaned and blew everything out of carb, installed new Reeds today. I let it idle for a while in my garage and took it for some high speed runs up my road. Like I said, she hits hard over 1/4 throttle. I still think my pilot is a little rich. I have a 38 I could try. Also smokes at idle but clears up when riding. Smells like good old 2 stroke oil.

 

[SS109]

Sorry for bring up an old post but that is dead on how my bike runs. From idle to maybe 1/4 throttle it blubbers a little. It gas gotten better after I put the clip on the very top clip position and put a 40 pilot in it compared to the 45 that was in it. It used to do it in first in second. Now it's mainly first. I looked tonight and it does have the n1ef needle and number 7 slide. Anything past 1/4 throttle she runs like a raped ape. That blubber is very annoying to me though, and can't have it in the woods where I need power. It was about 55 degrees outside today and I'm at about 200 ft above sea level. 180 main, 40 pilot, air screw seems best around 2 1/2 turns out, n1ef needle at leanest setting. Idle screw is way far in which tells me something is not right. Cleaned and blew everything out of carb, installed new Reeds today. I let it idle for a while in my garage and took it for some high speed runs up my road. Like I said, she hits hard over 1/4 throttle. I still think my pilot is a little rich. I have a 38 I could try. Also smokes at idle but clears up when riding. Smells like good old 2 stroke oil.

Finding your proper pilot jet is the easiest to figure out. Keep going smaller or larger on the PJ until your highest idle on the air screw is approximately 1.5 turns out. That simple! From there it makes it easier to figure out your main and needle.

 

[(F5)]

Haven't we been here before?

At closed you should be on pilot. Unless the base diameter of the needle is too small (when throttle is closed fastest part of needle is still leaving a big ring around it) , then big fat wet droplets of fuel will be escaping past the needle and the nice spray from the pilot is irrelevant.


So yes, the needle can affect closed to open unlike the otherwise spot on description of what alters what.

Throw away that N1EF and get another needle.

 

[memphis2857]

Haven't we been here before?



At closed you should be on pilot. Unless the base diameter of the needle is too small (when throttle is closed fastest part of needle is still leaving a big ring around it) , then big fat wet droplets of fuel will be escaping past the needle and the nice spray from the pilot is irrelevant.





So yes, the needle can affect closed to open unlike the otherwise spot on description of what alters what.



Throw away that N1EF and get another needle.

To further clarify F5’s post. The needle sets in the main jet. So the needle jet is affected by the main jet. If you are on a stock needle still, start with a 175 main and 40p. That should clean it up but it’s still not going to run very well simply because the stock N1EF is a flaming pile of poo and needs to be pitched in the trash bin.


Sent from my iPhone using Tapatalk

 

[(F5)]

Cmon say what you really think

 

[gasman88]

I ordered a couple different needles the other night. They were recommended in some post on here. They are n3cf and a N3EG. Hopefully they are better than this peice of junk one.

 

[(F5)]

If they aren't I'll buy you a puppy. But postage is pretty steep from here so I might have to package it separately.

 

[gasman88]

Got a bunch of different sized mains and pilots. Needles haven't came yet. Here it is running with a 178 main, 40 pilot, stock needle at the leanest with #7 slide. Think i might put the clip down at least 1. It runs great, no lean symptoms or rich symptoms. Smokes while warming up, choke on or off and clears up. I think my air fuel screw is around 1 1/2- 2 turns from seated. Makes me worried to see little smoke. I am running smokeless/asheless amsoil semi synthetic. Low flash point. Something like 175 degrees. I also have mogul 800 to try. Installed new boyesen power Reed's.

I started with a 180 main, 45 pilot, 3rd clip position and the air/ fuel screw was useless. Idle all the way in. It was a dog down low. But as you can see in this video, it's not a dog anymore. Opinions on the profession 2 stroke whispers? Should fatten it up just a little? 42 pilot, put it back on 3rd clip position? Whatever combination i ended up with really opened the bike up. Now i just need a new coolant overflow bottle because i stupidly put a hole in mine with a torch. Not happy about it. https://youtu.be/Z9NdNtlmMOY

 

[(F5)]

As long as you are running 40:1 with a reputable oil it will be fine. Don't listen to the crazy ratio lunies. You'd run more oil if the bike was higher revving but the 300 isn't a roadrace engine. I used to run motul in my race bikes but it is expensive. (Oh no, not an oil thread. . .run@!!).


You could take the overflow to a bumper repair place and see if it is weldable plastic. Doesn't matter how ugly it looks hidden away so you'd tell them that.

 

[jerseymike]

I know this is an older thread, but Im an older guy. How do you know what needle you have? where is the # stamping on it? I have no writing on mine. Same thing on the slide.