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The fuel injected small engines seem to go really rich when not loaded to limit rpm. Sort of a poor man's or rudimentary rev limiter. If it stayed lean with no load it would over rev to the moon. I run Stihl 500i chainsaws that operate this way and have noticed it at the track as well. I myself have a 22 150sx, was hell bent on staying away from tbi but probably should have went with one being im slow and nearing the 40+ crowd. Lol
They are hitting the rev limiter in the air. I have a 150sx and it runs clean.
Has anyone been able to actually mod the 125/150 engine? Other than pipe/silencer there doesn't seem to be much out there.
I have not done this myself, but there are tuning kits available. From what I've seen most guys are also going with a new head when they do these tunes.
https://sbmotoperformance.com/product/tsp-ecu-reflash-module-erm/
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What a piece of work you are.. this is Vital so hard to tell if I am talking to a 14-year old or not, but you are doing everything to insist confidently that you are right without any evidence or credible background experience. You are jumping around with your come back comment now saying things like "carburetors have certain advantages" which is the only thing I said.. they make more peak horsepower because of better atomization... this not my suggestion.. it has been shown in back to back testing of well jetted carbs vs EFI on the exact same motor many times over the years by people asking this very same question about EFI vs carbs. Fuel injection will not make more peak power over a carb by itself, but it has other advantages. Is that so hard or do you just want to be a hard ass? Oh, you have a KTM, so maybe I hurt your feelings?
And no, I don't google my information. Next to my mx bikes in the garage is an 800 hp car with an engine that I built, including designing the solid roller camshaft and setting up the optimal intake runner volume. I have been building high performance engines for almost 50 years. I was part of the championship winning race team for Bentley Warren Racing. Bentley was well known as a winning driver in the USAC Championship series as well as the Super Modified/ ISMA series. He won many championships over the years. He also raced a few Indy 500's and Formula One races. And you?
In September, I met a kid at the local track had a modified 2024 or 2025 TC125.
He was absolutely ripping on the thing. I could tell from the sound it was fuel injected.
I asked him about the bike and he told me it was fully worked over (ported, remapped, pipe, etc).
He said it wasn't as good as some tuned carbureted bikes he's ridden, but that it was pretty good.
I specifically asked him about top end and over-rev power and he said that was where it lacked.
I think he told me who did the engine mods, but I don't remember.
@Smuffers , that's cool to see a tuner available for these things. One of my chief complaints about TBI two strokes is that there's no way to change fuel and timing at the track. Hopefully one day, all the manufacturers will follow Yamaha's lead with a tuning app for smart phones, but in the meantime it's great to see the aftermarket responding with products like that.
Sure you did.
Interesting, yeah just seems like there are very few tuning/mod options available, which is a little weird since they've been out for a few years. I'm guessing they're maybe a bit hard to ecu tune?? But that is just a guess.
The current version was released as a 23 model. They are locked ECUs. But lots of tuners tune them. Twisted is one.
2025 model year TBIs all received updated mapping from the factory. They are very different from the 23-24s.
Twisted no longer does tuning on the 125/150.
Yep, I have a 25 300. I also had a 23. Newest system Introduced in 23, it’s the same system in 25 just improved. I’m not sure what you think is very different besides the mapping, maybe you know something about that I don’t. I wasn’t aware twisted stopped tuning the small bikes.
Clearly the move to a carb'd Beta RX350 smoker is most logical.
Back to back handling 22 YZ/24 SX. The SX felt like there was a magnet pulling the bike to earth. I had more confidence and comfort. Same for a 23 carb'd GG MC250.
Bought the SX and TBI sets you up for the dealer having to trouble$hoot. I'm on my second cylinder(chunked piston above the rings), it all went to shite after 80hrs and new cyl went 5hrs and got a seizure.
Sucks you had those issue's. Did you see MXAs video comparing the two?
I find it’s just like working on any modern fuel injected car (did that for a living) even comes with a diagnostic tool. That can be confusing if people aren’t use to it, but maybe simpler after you get the processes figured out.
They can foul plugs, I find that kinda interesting
I understand, but if I end up with a stone or footpeg stuck in the crankcase, it's handy that they're available. I only have one motorcycle. Getting these parts has been very difficult, sometimes requiring a 10-month wait. That's why I'm hoping someone knows if it's improved since then.
3 months for a piston in Italy. Lucked out and got the last one of the warehouse... dealer told me to order parts 2/3 months before i start maintenance because parts may take that long to be delivered.
MY 2024 GasGas MC 250 2t has been a great bike, i did my first top end at 40 hours and it NEEDED to be done... piston was fried... not a revver, they just won't last longer.
Slapped first size I piston after getting the cylinder measured. I'm now at 46 and it's fine.
I plan on doing another piston at 75/80, ride it few more hours and sell it before 100 mark...
Yeah, I didn't get a tool from the seller. If there was one in '24, KTM doesn't sell it. It came with a WMR re-flash, flawless performance/ride-ability. Any who, I lean towards KTM releasing bikes/parts with issues and that's where tpi/tbi becomes a burden. Just not sorted out as well as cars.
Pit Row
The mapping from 23/24 to the 25 was the major change. From what I've read, it was a significant improvement. I'm not aware that there were any other significant changes.
I think the tuners in America just gave up. Look at EMX125 in Europe. The fastest 125 class there is and they are running the EFI models.
While back in MXA, Twisted stated he is not remapping the 125”s, feels factory setting are safe for a reason, maybe something along the lines of when the rings wear they need to compensate for richer settings? Anyhow, KTM took a big chance at 2T development and for this their small bores need more development? Whats worse, Kawasaki”s hand job or KTM pushing the 2T development forward….
We've got a lot of time on the TBI 125's. Big believer in the TSP stuff here. We use the TSP ERM Mapping & 12degree Piston & Insert on our 25 125SX and will for '26. The kiddo was able to rip a couple holeshots at the LL regional and qualify for Loretta's in 125C. Granted it's only the C class, but there's a lot of talented rippers at the regional / national level on the gate. The bike proved fast enough to rip great starts against a gate full of petcocks & carbs. He also ripped a bunch of great starts at Ponca as well. It's been a lot of fun working on this with the kid and proving these TBI's can rip.
The mapping seems really solid on the 25 & up bikes off the showroom. Dealers also have the ability to upload a performance map meant for a FMF system that is also strong. That's my 2 cents. #10 Spring Creek LL Regional (Wish this pic had sound.)
Nothing but trouble for my kid's 2023 250SX. Been to the dealer a few times. It has never run right.
There is a ECU dongle, plugs in under the seat, the bike will flash any saved error codes when it’s used.
Had no idea the mapping on the 25s was different. I don’t recall seeing them mention anything about that when the bikes dropped.
Hard to say what the real story is. My shop told me they've rebuilt two 250 motors (for the same bike, same owner) that each grenaded at about 15-16 hours. The mechanic, who is very talented and experienced, showed me the pictures and they were gruesome, like damage I'd never seen before. KTM warrantied it the first time, but not the second. The mechanic believes there's some kind of tolerance or metallurgy issue in the crank or rod bearings.
I have a good buddy that I ride with that fouled a plug on his yz few rides back. Left us on the side of the trail for about an hour and a half. Bike had about 10 hours on it.
Does this mean he should light it on fire and tell everyone the bike is a peice and in no way shape or form did he have anything to do with that plug fouling?
Another friend dropped a valve in his crf at about 45 hours.
Another crf blew out the rear spokes landing off a triple.
Another friends oil pump failed on his yzf and sent shit flying all in the top end.
I had a oil pump gear fail on an xcf that caused some damage in the top end.
What are we doing here?
Wow, you guys are giving me the willies with all this talk of problems with the TBI Bikes. I just picked this up a few weeks ago with thirteen hours. The only thing i've noticed is some spooge on the silencer, other than that it ran great.
Granted, it still had some gas in there from the previous owner, who bought it from someone else.So i'm not sure how old the gas is, but I put some fresh premix in the tank to mix with the old gas.
So far so good, the bike is very nimble, but actually felt a lot like my 16 350 XCF W that I've loved as well.
The best mod we have seen from customer feedback on all the two strokes are RK-Tek heads.
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