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There are tuners out there who have figured out how to remap the ecu’s on these things. I had my 23 125sx remapped and it runs great now. In stock form, not so much. I used Tpituning.com for mine.
Casting issue aside that is the most uneven wear I have seen on a piston in 50 years.
Too bad I live in europe, tempting
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Did you get a stock piston kit or order direct from Vortex? Updated piston? I have 60hrs on my 300sx, pretty much all hard time in the sand, I”m wanting to do a top end but not sure what piston to get. Sucks about the 125 issues…penalty for taking the lead I guess. My 300 has been great, but right from the start I thought I heard/felt some detonation in deep sand, so I started using C12 50/50 with pump gas. I also have John Ross remapped ECU that really smooths out the big mid range hit and allows more top end over rev. The swingarm buffer & rear chain guide have been on back order for months, I found some new oem take off”s on eBay …
Based off this forum I had my dealer order the updated vertex with the slightly shorter skirt.
Can you take a photo of the part# when u get it? Appreciate it.
Thanks
For those of you who had the TSB done, has that fixed your issues with your '23 bike? I'm looking at picking up a 125SX in the next few months, but am wondering if it's better to go with a carb bike or the new EFI. There's some pretty significant elevation change near me, so the carb bike is giving me pause. TIA.
Well, I go back and forth from 600-1400-4500 ft regularly with my carb TC125 and carb MC250/300 and almost never touch the jetting. It's not as horrible as people like to make it out to be once you have it set properly (per long thread in tech section). I'd rather swap out a few pieces of $5 brass and $10 needles every now and again than deal with thousands of dollars for ECU's, remaps, trips to the dealer, etc.
That’s a pretty solid change in elevation. I’d be moving from 5K to 7.5K pretty regularly, so sounds like jetting shouldn’t be too fussy.
I jetted a MC125 for a rider who moved to CO. He rode it from Sweeny, to IMI and Thunder Valley, so 4200, 5030, and 6200ft. He had to make very small changes between those tracks, basically 1/2 to 1 needle clip or maybe also 1 pilot and main size. Keep in mind, this was to make the bike absolutely perfect. It likely would have been totally rideable on the same jetting.
Good leaded race fuel makes the jetting more constant T2 VPR U4.4 T2 is VPR just premixed.
I might need to get one of these bikes
I just picked up a 23 125XC, same bike with an 18 inch rear wheel. I’ve been doing a lot of research on the subject.
From the fb groups people are satisfied with them generally from what I can tell. I know people had issues with the 125, but I see a good number of people that are happy with them.
I have heard conflicting reports on which type of fuel to run. I’m going to start with the manual’s suggestion and go from there. I don’t have a lot of time on mine yet but plan on getting a couple of days riding in this week.
Good move following the manual with the new 125.
Changing fuel type, on an injection model with a basic ECU which has no way of monitoring AFR or fuel type, isn't the smartest without re-tuning or at least a dyno run to confirm you're making optimal power and doing it safely.
At best it may be passable, more likely it won't run as well as the correct fuel. At worst it will be rich and lame or when adding an oxygenated fuel perhaps lean enough to be dangerous.
I rode mine twice this weekend at the local track. The first day was fine with no issues.
The second day on my fourth lap, upon landing from a small tabletop, the engine starts cutting out. I pulled over to side of the track and looked the bike over for anything obvious. When trying to restart the bike, it would not idle. I had to give it a decent amount of gas to keep it running. I was barely able to get back to the pits.
I let it cool down and tried restarting, but it still had the same issue. The bike has 9.2 hours now. It hasn’t been flashed since April at the latest so I’m hoping that will fix it, but I promise you, I’m already regretting it.
I’m already thinking about trying to flip it once I get this problem rectified.
Pit Row
It’s funny how the YZ is quickly becoming a better and better deal. Pretty soon, it will be lighter and faster than the Austrians. Kind of like the ‘23 GG was (and the Husky KTM used to be).
So looks like I made the right decision to wait for the 2025s..
Bummer to hear, man. It sounds like the FI 125s just aren't quite there yet. Best of luck getting it sorted.
Yeah, I think I'm gonna pick up a '22+ YZ, or find a carbed Austrian bike. The YZs around me are always so clapped, which sucks.
This sounds like possibly a bad electrical connection/ground/kill switch.
It ended up being the spark plug. I’ve never fowled one and the bike would still run somewhat.
I changed it just to see and sure enough it started right up and ran well. It is still a little rich which I can’t do much about.
I’m still pondering flipping it to get a YZ just to have something that I can work on.
Strange. EFIbshould never foul a plug…. Maybe the newest update would help?
My son has a 2023 KTM 250SX with under 10 hours. Took it to the dealer on Saturday, it wont light up, just cranks over. We looked at the usual things but I'm lost with all the wiring and sensors. I think simple might be better.
The new EFI bikes definitely foul plugs. My 300 and other people I know with the new EFI bikes have fouled plugs. First thing I’d check if you can’t get one to idle or start properly
2 strokes will always coat the plug with oil and foul them. It’s just how they are. Simple fix is replace the plug 1st if there is a problem or as part of maintenance replace it before it fouls. I had a KX500 that would foul plugs so much I kept a plug wrench in the woods.
I have not fouled a plug on a carb'd 2 stroke in over 30 years. No exaggeration.
Yes, fouled plugs are somewhat common on the TBI bikes. Especially early on with the original mapping they were using. They seem to have diminished this quite a bit with mapping updates but it still occurs due to variables from the user that the mapping cannot account for (fuel, oil, ratio, riding habits) and a plethora of other issues related to TBI (TPS adjustment, clogged CCPS, other flaky sensors and electrical issues, etc). More complicated $h|t, more $h|t to break and try to troubleshoot.
I didn’t say they don’t. I said they shouldn’t. I haven’t fouled a plug on my 250 2 stroke since I’ve owned it.
to the guy fouling plugs on there kx500 your jetting must be shit.
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