2022 ktm 125 running bad

[Rob22450x]

Well don't do to much tell you change out all fuel filters and check fuel lines first imo 

[tekcor]

I had a stock 2019 KTM 150 SX that had this exact problem.  They bog and have no power off the bottom.  Two options.

1.  Follow this jetting guide to the letter - https://www.vitalmx.com/forums/Tech-Help-Race-Shop,42/KTM-HUS-125-150-250-jetting-thread,1363394

**Updated 7/28/2020**
'17+ 125/150 jetting
Pump gas/race gas mix, C12 straight
MJ 490
PJ 32.5
Needle Jet S4
AS 1.5
slide 5.0
Needle 42-74 on the 2nd clip (Yamaha 284-14116-H4-00)
Needle jet S4 (KTM part #55431021400)
PV 1.75 turns in from all the way out.
Fuel mix 40:1

2.  Buy an Lectron.

I went the Lectron route, but still didn't like the powerband on the KTM 150 SX, so I sold it.

I sold the Mikuni kit I made from the jetting guide to a friend who said it is working well for his kid's new KTM 125 SX.

Good luck!

[777654321]

@mog is a jetting expert.

[Aaron Gastrich]

Check or replace the jet block gasket before attempting to jet it.  Known issue with the Mikuni carb. 

[traskrat]

This is a easy fix- its called buy a Lectron

[85sx Braap]

Just now, traskrat said:

This is a easy fix- its called buy a Lectron

Money don’t grow on trees

4 minutes ago, Aaron Gastrich said:

Check or replace the jet block gasket before attempting to jet it.  Known issue with the Mikuni carb. 

Did that already 

5 minutes ago, Aaron Gastrich said:

Check or replace the jet block gasket before attempting to jet it.  Known issue with the Mikuni carb. 

Already did that

[traskrat]

Just now, 85sx Braap said:

Money don’t grow on trees

Sure thing Son, and a poorly running 2 stroke is miserable, especially if the fine art of jetting is not mastered.

[85sx Braap]

20 minutes ago, Rob22450x said:

Well don't do to much tell you change out all fuel filters and check fuel lines first imo 

The bike has 1.5 hours on it

[Rob22450x]

5 minutes ago, 85sx Braap said:

The bike has 1.5 hours on it

Yeah but you never know I could be anything could be running to lean could have something in the line fuel filter could be destroyed fuel pump could be going out with that many hours is running like shit I take it back

[Graydon Mccool]

23 hours ago, 85sx Braap said:

Hi I just bought this ktm 125xc. I just Started it for the first time and I noticed it runs like garbage. I installed a jd jet kit but it did nothing. Im running a 460 main, 32.5 pilot and the blue needle. Only solution I have right now is to sell it and buy a Yamaha?.

Is the choke out 

I’ve done this before. Almost sold the bike actually and it turns out the choke was on the whole time. 
now I never choke my bike 

[mlatour]

49 minutes ago, Rob22450x said:

Yeah but you never know I could be anything could be running to lean could have something in the line fuel filter could be destroyed fuel pump could be going out with that many hours is running like shit I take it back

What are you talking about, this is a carbureted engine,

simple petcock fuel strainer, no fuel pump...

 

A Lectron isn't the answer if someone doesn't know the basics of a rich/lean acting engine.

 

Edited March 3, 2022 by mlatour

[85sx Braap]

3 minutes ago, mlatour said:

What are you talking about, this is a carbureted engine,

simple petcock fuel strainer, no fuel pump...

 

A Lectron isn't the answer if someone doesn't know the basics of a rich/lean acting engine.

 

I’ve been working on bikes for years I know the difference from rich and lean. I just don’t want to spend the money on a lectron.

[Rob22450x]

3 minutes ago, mlatour said:

What are you talking about, this is a carbureted bike,

simple petcock fuel strainer, no fuel pump...

Yea true hmm you got a lemon my guy take it back 

[85sx Braap]

29 minutes ago, Graydon Mccool said:

Is the choke out 

I’ve done this before. Almost sold the bike actually and it turns out the choke was on the whole time. 
now I never choke my bike 

No the choke is in 

[Rob22450x]

10 minutes ago, Rob22450x said:

Yea true hmm you got a lemon my guy take it back 

Or maybe some kind of carb jetting problem idk if it's that new take it to a ktm dealer warranty my friend 

[olderthanyourdirt]

17 minutes ago, Rob22450x said:

Or maybe some kind of carb jetting problem idk if it's that new take it to a ktm dealer warranty my friend 

My first thought too. If that new, back to the dealer.

[mlatour]

Quite simple actually, it's a race bike, implying the person wrenching on it must first have basic knowledge of fine-tuning it.

The OP is riding it in approx. 40°F ambient temps, the stock settings are meant for 70°F

That alone typically warrants going 1-2 steps richer on all metering circuits.

 

JD jetting 'kit', Lectron or Smartcarb aren't a miraculous cure if a person can't yet discern rich/lean by 'feel'

as any carb will require experimenting / tuning if you want your engine to run optimally (not just good enough)

With the right settings you can probably achieve equal or better performance / driveability from the stock Mikuni versus any of these carbs.

(the YZ125 uses the same carburetor and pretty much 'perfect' jetting from 2010 to 2021, what does Yamaha know that KTM doesn't?)

As the YZ chart I posted earlier, the KTM factory service manual likely has a comprehensive jetting chart that covers ambient temp changes.

 

Also keeping in mind that no 60-125cc 2-stroke MX race engine is going to respond well gunning

the throttle wide open right off idle (especially in cold weather) as they aren't equipped with an accelerator pump.

If riding below 6000-7000rpms, you must keep a finger on the clutch at all times ready to slip it if you need instant throttle response.

 

Edited March 4, 2022 by mlatour

[yz j]

A bog is typically lean. I would start by going richer on the pilot and needle until it goes away. 

[GezR]

Might be worth checking the reeds. I know it's a new bike but worth ruling out.

[traskrat]

2 hours ago, mlatour said:

Quite simple actually, it's a race bike, implying the person wrenching on it must first have basic knowledge of fine-tuning it.

The OP is riding it in approx. 40°F ambient temps, the stock settings are meant for 70°F

That alone typically warrants going 1-2 steps richer on all metering circuits.

 

JD jetting 'kit', Lectron or Smartcarb aren't a miraculous cure if a person can't yet discern rich/lean by 'feel'

as any carb will require experimenting / tuning if you want your engine to run optimally (not just good enough)

With the right settings you can probably achieve equal or better performance / driveability from the stock Mikuni versus any of these carbs.

(the YZ125 uses the same carburetor and pretty much 'perfect' jetting from 2010 to 2021, what does Yamaha know that KTM doesn't?)

As the YZ chart I posted earlier, the KTM factory service manual likely has a comprehensive jetting chart that covers ambient temp changes.

 

Also keeping in mind that no 60-125cc 2-stroke MX race engine is going to respond well gunning

the throttle wide open right off idle (especially in cold weather) as they aren't equipped with an accelerator pump.

If riding below 6000-7000rpms, you must keep a finger on the clutch at all times ready to slip it if you need instant throttle response.

 

All true sentiments, the OP says he knows the difference (symptoms) between rich and lean,

the beauty of a Lectron or SC is that a lot of the “guess work” can be eliminated as the carb gets delivered to you, after answering appropriate questions on the order form, by the factory w settings based on altitude, temp, displacement, riding style etc…….at least mine did.  But yes- that do cost some $$.  
 

anyway you slice it, a new 2022 shouldn’t behave this way, even stock w fat jetting and spooge dribbling down the silencer