Upgrade to enjoy this feature!
Vital MX fantasy is free to play, but Premium users receive great benefits. Premium benefits include:
- View and download rider stats
- Pick trends
- Create a private league
- And more!
Only $10 for all 2026 SX, MX, and SMX series.
Do you have another bike you can dyno today in order to make sure your dyno is reading correctly?
That’s crazy. Something has to be wrong. Two stroke performance on YouTube got 36.9 on his dyno.
Interested to hear what comes of this.
Yeah, me too lol..I chose to edit the original post as to not start a war over it and chose to try to build a bigger table and have more chairs at it over building a wall with KTM. We will see how it goes and I am trying to sort out some things now. More updates as this comes along.
MXA just did a 125 shootout and unfortunately the sx/tc 125 had issues during the test that was not fixed.
J
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
i'm holding off on that for right now to see if the issue can be resolved with KTM.
Nothing new to report, got the bike home and tripped an Fi light when it started..back to the dealer for a reset.
That's frustrating man. Keep fighting the good fight. Was the famous hit the starter while engine was running Fi code?
No, the Fi light is just steady on, no flashing. I think that it could have been when I drained the tank and started over for the gas and oil mix. I DRAINED the whole system, bone dry, lines and all, nothing in it at all.
So when I added fuel it took a while for it to start and I had to tickle the throttle and eventually is fired and I think it saw no fuel for too long and maybe threw a code.
5pm dealer reset, tbh, this back and forth to the dealer thing to clear codes is a drag.
How goes it with you? DM me if you want to discuss - J
Just saw this thread. I was the first guy that chimed in on the 300 thread asking if people were having 125 issues.
We have (2) of the 125's. Both of our bikes are completely unusable in the green map and frankly the white map is quite underwhelming.. I was happy to see MXA give an honest report on the bikes. Not to bash KTM but happy because everyone kept asking us if we were sure we were doing x/y/z properly and no one believed there could possible be this big of an issue.
One of the bikes actually threw a code on the FI light the other day. It still ran the same (shitty) for a while and started getting worse and worse until it just stopped running completely. So i took it to the dealer and they agreed to just go through the entire bike until they figure out what the deal is.
I’m in the same boat, back to the dealer tomorrow for a final plug in and check over, it keeps throwing codes, very low power output, (I dyno’d it), and it just doesn’t run right.
I edited my post bc I did go on a rant and bashed them and I should have given them the opportunity to make it right before doing so.
we will see, KTM did install a BR9ECMVX and said it should be better but I haven’t checked yet bc it threw an Fi code and was also told to use the white map only for now bc the green one has issues.
dm me if you want any more details on how this has been going, I have a lot of info.
good luck-
Went to the dealer, the code was for "fuel pump error", cleared it and its all set. I also learned an awful lot about some things about the computer hookup, what they can see and do, monitor, etc. and an awful lot about myself.
The new 23' connections to the dealer computer can monitor TPS, engine temp, battery, and also engine rpm and a slew of other things, very interesting to see it.
Here are a few things that I learned for the 125sx, (not sure if all of this translates to the 250-300sx, this is for the 125sx only).
After being the New England distributor for Renegade Race Fuels and having some in depth knowledge of the fuel and industry, a 2015 AMA National Championship winning 2 stroke motor for the National Enduro Series, (built a custom KTM 200 engine out of a 125sx for Ron Ribolzi, the owner of E-Line), building a Honda CRF450 engine that got a 3rd in the Baja 1000, guest mechanic for Cedric Souberays at Gillette Stadium, thousands of rebuilds, mods, happy customers, (not all of course), having a pretty solid reputation of having the ability to diagnose, troubleshoot, and fix thousands of multi brand issues and find workarounds, in regards to the specific nature of the current way that these bikes are being rolled out, see your dealer for any and all service work, trouble shooting, adjustments.
I wont publicly be commenting on any issues that may arise during use.
Maybe your bike was never pumping quite enough fuel during your Dyno runs and that might contribute to the numbers you were seeing. Just a stab in the dark on my part. So are you saying I shouldn't adjust my TPS? I was about to buy a TPS tool.com reader. Shoot me an email if there's any other cool things you learned. I'm Brock161.
Thanks for the update jbone
Fuel pump passed the test, this was a thought of mine as well but the KTM computer that knows what blood type you are says its fine.
I have adjusted many many TPS in the past with amazing results but apparently this one should not be touched b/c it is perfect from the Factory, will never need to be adjusted.
One thing I didn't mention is that I was told to never run the green map and run the white map only until I'm instructed to do so by the dealer. The mapping is having something going on with it.
That's funny because when i very first took ours back to the dealer they called KTM and when the tech called them back he told them it was a TPS issue. He told them specifically to not adjust the actual sensor but to set the butterfly valve between 1.5-2.5 degrees using only the fast idle screw AND the fast idle button. His comment about using the yellow fast idle knob immediately made me second guess everything they said though. The yellow fast idle screw should even be contacting the cam unless it's pushed in... Needless to say that didn't help anything at all. It was basically adjusting the idle.
FYI - I purchased one of the TPS tool plugs so i could test the voltage. Both bikes tested at .47-.48 volts from the factory and when you run the idle screws all the way out the TPS itself was set to .38 on both bikes. I played around with adjusting the sensor on one of the bikes and sure enough .38 was the sweet spot.
Also - spoke to a guy today who also picked up 2 125's and sent them straight to a well known 2 stroke engine builder up north to go through them before the kid even got on it. Even these guys could never get it to run right either. They said that for sure the powervalve is not acting right even after recalibrating it. They went back and forth with KTM and he says they ended up having to send the CDI back to KTM. Now i'm assuming that he meant the ECU and not CDI. He said he will keep me posted on his situation as well.
Man your comment about seeing the dealer for all service work is a major problem. The very first thing i tell parents of new racers is they better learn how to work on bikes or they're going to have a really short time in the sport.
I’m gonnna email you. J
What I find puzzling is that all the bikes are put on a dyno after final assembly. The final dyno check has a go no-go horsepower number. If the bike passes, a green light goes on and the bike is disassembled and put in a crate. If it doesn’t pass, it’s set aside for further investigation as to why it’s down on power.
so…..if the bike was that down on power why was it shipped? The only thing I can think is that KTM has the correct map and installed it into the ECU at the factory. After the dyno run, they lock the ECU for shipping. Once the bike is purchased, the bike is “woken up” as the dealer installs the “latest” map. I think this is where the issue is. Something got lost in translation with the available maps at the dealer.
KTM has the good maps for sure because I have several friends who work at magazines who rode the pre-pro 125 and they all said it was amazing and clearly faster than the carb’d bike from crack of throttle to overrev.
I feel for you guys going through this and I hope KTM steps up and makes it right.
They have been good so far, but I have to keep bringing the bike and forth to the dyno ($), and running it to get numbers and post back with them and it’s just kinda bummed me out.
we will see, thx- J
Pit Row
Looking forward to it!
My son knows a test rider that did one of the magazine shootouts and he told him the KTM for sure had issues and KTM didn't have an answer yet. They were told to only use the green map. I have seen some of the bikes run amazing though and a whole lot of people having nothing but issues. Off the top of my head i have now had 9 in person conversations with people experiencing the same issues. So i'm stumped. lol
Update - I'm now officially annoyed with KTM. You have some guys that are being honest and some guys that i'm not sure how they sleep at night. My dealer called me today to update me (dealer has been great so far btw) on what a guy at KTM told him. The KTM guy tried to bullshit him and say that the green map is for "loose" dirt and it runs like that for loose rocky terrain. And the white map is for normal conditions. I wasn't trying to be rude to dealer but had to stop him and call bullshit. I said I may almost buy that story if it was on an XC bike but the SX bike was designed for motocross and no motocross tracks are loose rocky terrain. They're just trying to make up bullshit at this point and trying to essentially say i'm an idiot. My 14 year old is absolutely furious with them now because all he needs to hear is "you are correct. We have a problem and we are working diligently to solve it." That guys bullshit "oh it was designed to spit and sputter and cut off in the air you silly little boy" about made him lose his shit today...
The MXA video said "white map only", I was also told this...I have no idea anymore. Green, White, ?
Im going to go dyno my bike again and print it out, and then take it to another dyno and print it out and compare whats going on with the curves and see if I can work with KTM on help fixing the issue.
check your dm
My apologies. I actually meant white map. They were told to only use white map. Just wanted to clarify on here for anyone reading this down the road.
Here is an update on the spark plug for the 2023 KTM 125sx, nice and clean and not very mean.
https://www.youtube.com/watch?v=kLkZzfhjKEA&t=27s
Making any progress jbone?
Nope.
The bike was given back to me "as it was set up from the factory and should stay that way". So, I can't keep throwing $150 out the window endlessly to keep dyno-ing it on a bike with mapping issues. Until I get an update for the ECU, it is pointless money waster. KTM is working on the mapping, the MXA video spoke of some of the issues they had.
The only way to discover if there is a map update available is for me to bring the bike to the dealer and plug it in. The dealers do not get an email or communication that there is an update, the burden is on the end user to bring the bike in and see, as if, by chance.
What I have done is attempted to communicate with my service dept and ask them to make a note of what version is populated from the cloud the next time they wake up a new bike and let is sit for the 24 hrs, so that I may be able to compare that to the version I have and see if its the same or a higher version.
If it's a higher version then I know to bring my bike in.
If you or anyone else would like more information on whats going on, feel free to dm me, I won't publicly comment on my feelings or air out issues, just post facts.
Thanks for asking and I hope you have a great CHRISTmas- J
Sorry to hear man. That’s a huge bummer. Even stranger that some say there bike runs great. Hopefully they come up with a fix soon.
I suppose it's a first world problem at the end of the day lol...I am sure it will get sorted, I can't move on it unless there is a new map to fix this issue so far.
My friend has a TC125 and he said that feels great, his buddy has the same bike, terrible. Nuts.
So is your bike rideable?
Can you not ask for a refund? Or exchange for a new bike?
I suppose it’s rideable but if the are saying the maps are jacked and from the other things I hear not sure I would want to test my faith this way lol.
I think it needs to be right and the risk of doing this all for another version of the same issue that may pop up is a struggle.
My head hurts - j
I wonder when tsp will have cracked the ecu on these and be able to offer some support.
Post a reply to: 2023 KTM 125SX 250sx 300sx deep dive EFI tune, mods, mapping, exploring the tech *YoutTube videos added* *Facebook Group added*