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Only $10 for all 2026 SX, MX, and SMX series.
I agree. I put it one notch higher and got used to it.
I know of multiple people that had low hours 300's that blew up on them.
I have three rides on it and it’s a wonderful improvement. I was never fully pleased this this motor compared to my 2021 300sx and their tune really closed the gap. It picks up a lot quicker, runs a lot leaner, and overall just runs way better. I can carry third now and it lights up way quicker with much less clutch that prior. I had every re-flash from ktm and imo it’s pathetic that a shop like twisted can develop a better map than KTM.(they are amazing so no diss to them)
Vertex makes the updated piston, 2mm addition clearance iirc
The Shop
Luxon 4-Post Bar Mounts
$189.95 - $239.95
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
If you want to try a forged 300sx piston, I will have some Wossners here today/tomorrow that are a better piston imo, I also have pin bearings and OEM top end gasket sets, (had to get them from Europe!).
Hope all is well- J
I”m not doubting you, I have just not seen one blown up myself. I do think map 2, the aggressive map felt lean with stock mapping, I started using C12 mixed with pump gas after thinking I heard detonation while riding in deep sand. These multiple people you know with blown up bikes…. Did KtM help them out with rebuilds?
Part# ?
Vertex does not make an "Updated piston" for the 300. At least not one with an updated part number that is different/unique that anyone can locate in any distribution channels I am aware of as a dealer.
The Vertex piston for the 2023/2024 300 is the 24244 A/B/C series which is the same piston KTM 300's have used for years even prior to the TBI bikes. Here is a screen shot from the Vertex website.
As for there being an "updated piston", from what I saw on here and elsewhere the ones being delivered in the bikes appeared to possibly be too thick with excess casting material at the bottom of the skirt. There seemed to be some indication that maybe this was a bad batch KTM received from Vertex and the ones you buy direct from Vertex should not have this flaw. So, it's more a matter of them being correctly manufactured and not an "update" with a new part number.
Well it’s likely the new pistons part number supersedes the old one. There was a email posted here from Vertex explaining the changes to the piston, I think it was posted in this thread even, do some digging and you’ll find it.
The problem was there before the TBI bikes, it’s not a “bad batch” and there is indeed a new piston with a shorter skirt to address the problem/concerns regardless of what the part numbers indicate.
The only email reference I saw was this one from Wossner, not Vertex.
https://www.vitalmx.com/forums/moto-related/2023-ktm-300sx-potential-is…
I think we're basically saying the same thing here and mixing words. Yes, I understand there is/was an issue and that Vertex may have corrected or updated the part. I was more addressing Sandman's thought or question that there must be an updated/superseded Vertex part number. There is not, as far as I can tell. If there is, Vertex has not done a good job of updating supply channels with this information. I don't think vertex has made a new or distinct part or part number. I suspect what they've done is more of a "mid-production run change" sort of quietly, as manufacturers sometimes do. Maybe there are still some "bad" pistons floating around in supply channels or on dealer shelves. Without a new part number, it's hard to say. All I know is I'd be inspecting pretty close any piston, especially a Vertex, that I'd be putting in a 300 right about now.
Probably had some parts out of spec for years, and it was never a problem until the engine redesign. KTM engineers assumed the piston spec is held to and that the old pistons would work fine in the new engine.
No one actually checks incoming parts at the plant (most likely) or they spot check and it is only the occasional part that is out of spec so it doesn't get caught.
Currently have the FmF fatty pipe on my 300sx, it’s good for Mx. question #1: Setting my bike up for woods/ GNCC riding, is the FmF gnarly worth it for improved low end/ lugging? Question #2: for anyone who has done the thermostat delete, what did you do with the sensor plug in? 2023 300Sx 70hrs on stock top end, has not blown up yet👌. Thanks…
Haven't been checking in much. What is the latest on reports for those with flywheel weights and ECU upgrades?
FMF fatty is basically a stock replacement. Gnarly always make the power very focused, and limiting imo. From all the reviews I’ve read PC is the best selection for the TBI’s.
The delete doesn't affect the sensor. Simply plug it in as normal.
Great..thanks…
I always had the same problem and people in the know have a solution (1/2 spline) not sure who fabricates them but the Factory guys always had the option of using them.
I’m at 50 ish hours on mine. After the radiator debacle, she’s been awesome. I actually raced 3 hare scramble races that were two hours each with no coolant and she still runs great. The loading up issue I think was related to running 40:1. I’ve been at 60:1 and it’s way cleaner. Everything measured ok so I didn’t do anything with the top end. I’m going to ride it until it blows up or until the 2025’s come out.
The PC pipe and PC 304 is amazing. Great midrange and more top end which is what this bike seems to lack. I made the switch from the 6500’s to the Cone Valves and the small bump absorption is next level with the cone valves. This bike is incredible.
Pit Row
Hi guys, considering trading my YZ 250 for a 2024 SX 300. Can anyone confirm if the 2024 comes stock with the shorter piston skirt? Or am I better off buying a SX 250?
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2023 KTM 300sx potential issue (pics and video) - Tech Help/Race Shop - Motocross Forums / Message Boards - Vital MX
I don't think there's an issue for the 24's. At least I hope mine is bueno. PC pipe and WMR re-flash...I like it a lot.
There is a new power valve kit for the YZ that gives it a totally smooth delivery, made by HITLIS. Makes the power more like the 300's, as in lugs better for rutted turns. Riders are saying it reduces arm pump .
24' piston specs are exactly the same as 23' and prior. The 300sx will also feel softer off the bottom compared to your YZ, it's also heavier and many private dyno's will show the 300sx making about equal peak hp to a YZ.
envious, bitter, spiteful
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