Should have got a 350 years ago...

Personally I prefer my 23 over my 17,19 and 22. I don't really feel the frame is too stiff at all and the engine on the 23 is awesome.

I do know this:

Everyone I've talked to that has ridden/liked 450s says the 23+ motor is amaze balls.

Yeah I have a 24 kx450 aswell and while the 450 definitely has alot more torque, the 23 350 is more like a mini 450 than the previous models. It also has a very responsive quick revving nature that makes the bike feel lighter an more fun. 

Back to back with '23, I'm stoked with my '24 300SX. Lifetime smoker, so there's that.

When are 350s typically in need of a top end rebuild? 50, 75, or 100 hours? Many variables there I know…

Reason I ask is I am looking at a couple different 350s and balancing the value of a 15 hour bike vs. a 35 or 55 hour bikes. 

FWIW - I just bought a used 2022 KTM 350 SX-F with 50 hours for $5250 that looks close to new (but he did remove OEM plastics when new and put them back on when selling, also ran an aftermarket exhaust of some kind). Previous owner was religious about oil changes per manual (every 10 hours, I think) and used Motorex 10W50 as it states and staying up on air filters. I figured it was a reasonable "roll of the dice" given my research on the 19-22 bikes seems to indicate 150+ hours on a top-end and before the valves need to be adjusted, etc., is common.

I had a second 2022 350 SX-F lined up for $6500 with only 4 hours, but when I went to pick it up the Seller said the battery was dead and it wouldn't start, the pics didn't match the hours/newness, so I decided to cease and desist. In this case, the 50-hour bike seemed like the better bet. Time will tell. 

I say this ^^^ as a calibration point (hours, $$$ and condition) and to see what real-world users have to say. I am currently just a new real-world owner, have never ridden it.

Great question - Bueller? Bueller? Bueller?

I’m at 50 hours and have no plans on touching the engine anytime soon. I was thinking I would check valves to replace the top end around 100-120 hours 

That’s a nice snag at $5250! You are correct in that not all hours are the same. I get the sense that a well kept bike under 60ish hours is probably low risk.

A friend of mine has 90 some hours on his ‘18 it’s never been opened up and shows no signs of needing anything. My ‘23 has 28 hours on it with no issues. I’ve also read of guys going 200 hours or more with no issues. 

Hours between top ends depends vastly on the rider's skill level and how hard they work the bike, how well they change oil and air filters, engine CCs, and what oil they use.  I pulled my last 450 top end at 100 hours, and it looked great.  Didn't need to be changed.  I now do mine about every 150 hours unless the bike is giving indications it needs it sooner.  I'd say that if a rider is a vet, doesn't beat the rev limiter to death, changes oil and air filter every 5-6 hours with good oil, that ~120-150 hours is a good top end frequency.  I know local fast kids who race 250Fs that have to do their top ends every 15-20 hours. I'd say that's 2 ends of the spectrum on the topic.

My 2022 350sxf had 89 hours on it ($5500) when I picked it up in Feb 2024. Feels and sounds really good. No immediate plans to tear into it. Linkage bearings were toast though. i did have to replace them. 

Not recommended but I just worked on a '21 with 600+ hrs on it! still ran great only had 1 top end...crazy, but good maintenance 

Old vet intermediate rider here .  I have recently rode a 24 (3hrs ) husky and yesterday rode 24 KTM (10hrs) currently have a 22 with KYB and tzr mapped ECU FMF slip on  . I have to say I like the husky better as it doesn't seem as stiff for some reason and cornered better , both motors are hands down better stock than my 22 . I was thinking on getting a 25 but I think I'll rebuild mine (85hrs}and maybe have it ported or big bore it (tzr) and pick up another 450 as a second bike 

^^ that’s not a bad idea. I think I would rather have two bikes than just a 25 350. Plus the fun factor for the 350 is the high revs for me, so a 22 with some work would be perfect 

How do you like the TZR remap on your 350?

It's outstanding. I've had 2 vortexes with maps by xpr and TD and while the TD map was better out of the 2 . The tzr map is so close and a 10th of the cost . I actually think the tzr map runs cleaner but I only ran pump gas in all so it was a fair comparison. All are much better than stock for sure . 

So i bought my first 2020 sxf350 today 😃 after 10 years of thinking of one.

mods that i will be doing:

Steel oilpump gear.

2stroke cage.

vortex ecu.

cc wp forks.

maby a exhaust if i can get a used one for cheap. Any other things that i should consider ?

Honestly you should have put that money towards a 23+

To each their own, I liked my 2019 350 way more than my 24. I ended up selling my 24 after 15 hours because I didn't gel with it.

1. Congrats on the new bike! Good buy

2. Don’t forget possible gearing testing (+1 or 2 on the rear, track/conditions dependent) and the vented airbox cover to go with that 2T cage.

3. I really liked this PC linkage (requires a stiffer spring rate for proper function) on those years: https://www.rockymountainatvmc.com/parts/pro-circuit-linkage-system-p

More ideas here as well: https://motocrossactionmag.com/mxa-tech-spec-12-things-about-the-2020-ktm-350sxf/

Dirt Tricks cam chain tensioner (oem fails on occasion). Enjoy the new steed. I love mine enough I just spent about $4000 on a refresh.

Rode a -25 SX-F 350 last week. Completely stock except the suspension that was built.

Great bike, and definitely better than the 350 from 19-22.

In what ways did you feel it was better? The 23+ definitely make more power in stock trim. Curious what else you noticed. 

I did top and bottom on my 22 fc350 at 100 hrs and it looked like new when we opened her up. I usually sell at 100hrs but I love this bike so much   I decided to keep her for another 100.

I ran 2) 350’s to 145 hrs and just decided to rebuild mine instead of buying new as well. My engine guy said it looked excellent as well. Installed prox conrod, oem piston kit and reused the valves per his insistence. Very impressed with Ktm durability.

As Keefer would say (peace and love), when i went to replace my piston at 42 hours i checked valve clearance. I noticed my intakes were below spec and my exhausts were at min. My check at 26 hours had them well within. So i pulled the head apart and found the intakes well pitted and the mating surface being stretched. New valve time with seats recut, yay at 42 hours. Mind you this is at a A level pace with most of the hours on a deep sand track, with the best power near the limiter i sounded like a agro teen out there trying to keep up with my lads on 450's. 

While I don't disbelieve everyone's intervals being higher, just stating my experiences being much less. I dont blame KTM's quality as I'm stressing the engine about as much as one can. Any smaller bore brand would be the same or worse intervals for what i put it through.  

The fun side is since i needed seats cut I sent the head to twisted to have the seats flowed as well, the stock seat to bore is pretty sharp. Had them send back a tuned vortex for T4 and their high comp 350 piston. These changes to the engine help tremendously to bridge the gap to 450's on deep days so I don't have to rev as far to keep pace. Same free reving 350 power and feel with just more meat everywhere. 16 hours on this setup and the valves haven't even moved a half thou. Long story short if your a faster rider around 200lbs riding deep sand trying to keep pace with 450's just know your intervals are going to suffer. 

That is an awesome looking bike man! Love it

The engine was the main part. But i really liked the handling of the bike as well. I never had much experience on the 23-24 frames but the new -25 felt fine, at least on the track i rode on (intermediate).

Question for the 350 experts here.  I have a 2022 FC350, hopefully someone can relate that has done something here, but anyway, in 1st  - 2nd gear when you are just going from the pits to the track or whatever, when you give it gas, the initial "jerk" of the bike is really damn harsh.  When you are on the track at race pace, it is not really all that noticeable, but when you are just trying to ride, it is annoying AF.  My bike is stock other than suspension work and 1 up on the rear sprocket.

I am getting to the age where reality is hitting and my performance on the track is starting to take the joy out of it.  I am considering doing a bit of re-purposing of my 350 to make it more of a woods bike, but would like to smooth it out a bit.

Thanks for any suggestions!

^^^ FWIW, a ‘24 does the same.