YZ450f to feel like KTM350?

I’m curious about this as well.  I’m on a 2021 YZ450FX 
 

I rode a 2023 350XC KR edition a week ago..,which happened to have Cone Valves…and it was absolutely amazing…I loved the power delivery…enough low end that it didn’t feel like it wanted to jump out from under me but didn’t feel slow, but pulled as long as I ever needed it too (which has been my issue with every 250f I’ve ever ridden)…the suspenders didn’t hurt the situation at all that’s for sure…

I think a 350 will be my next bike…one way or another.

I don't know about making it like a 350, but retard the timing for less hit and more overrev.

You could make the engine characteristic similar to the 350 but because of the extra engine inertia it will still handle like a 450.

This is the setting i ran everywhere before my ecu shit itself and i bought a vortex. This map takes the initial snap out of the engine that can make the bike jerky through corners but then runs strong through the rest of the power. 

If you wanted it more like a 350 you could try retarding ignition at higher throttle % up to around 6000-8000 rpm and then return it to stock for the top end rpm. That would allow bottom and mid but let it pull hard up top

I know exactly how to make it feel like one…

Step 1: wash YZ450F

Step 2: List YZ450F for sale

Step 3: Deal with terrible trade offers until someone finally meets you with an agreeable price.

Step 4: Go to KTM dealership and purchase a 350.

Step 5: Ride said 350.

Is any chance for a jap to make a 350 over?

Haven’t heard anything pouting to one being made yet.

would it be easier or closer to make a big bore YZ250F with dual injectors, vortex, exhaust feel like a 350?

Just buy the dang 350 lol

Joe owns a 350

The Japanese brands don't want to cannibalize their own sales but its as if they don't even realize the number of sales they're losing to the Austrians because of their stubbornness.

I agree…I don’t get it..,,for me, besides mini’s, I’ve never owned anything but Japanese…I’ve never been able to justify the extra $2k-$3k for one…but I think for my next bike I’m going to make the leap and do it, just to own a 350…

I ride sand tracks in the Netherlands and I'm too heavy for a 250 so I choose the big blue pig.

I haven't ridden a 350 yet but this mapping calmed my 450 down and I have a ton of fun with it! Coming from a Husaberg FE 450 I would say this is close but the app leaves all doors open to make it to the bike you like.

My favorite trade offers were always someone wanting to trade me a pocket bike mini street bike lmaooo

Its getting too late to join party. Next new bikes they will come out will be E-bikes. 

If Yamaha had YZ350F I would buy one. 

I’ve had a 350 since 2019. Just adding to the OP that making a 250 feel closer might be easier because 450 will always have the engine mass.

Other reasons someone might like the Yamaha is the ergos, the chassis compliance, the suspension?  

Just do what the X-County world has done and just move on from companies that won’t make bikes you want. 

Sadly no. I’ve ridden a 350 from 2014-17, jumped to a YZF 450 from 18 till 21. This 22 season I went back to a 350 and i wish i did it way earlier. 
 

I know exactly you’re feeling and I’ve tried allot of things with the YZF wich cost a shit load off money over the years. But you’re never gonna get that light feel a 350 does. It moves that easy and light and almost no engine braking wich is on the YZF the worst part, later models are a bit better. 
 

The Tuner app is cool, but you can’t really that much. I went with a GET ECU later and took a Dyno run for a clear mapping and took as much as could engine brake out off it. It was a allot better then the tuner app could do. The GYTR head also smooths the power out allot better, together with a Rekluse clutch kit, for some more engine braking reduce. The bike was in the allot different and liked it at that point until i rode someone’s 350….

The best way and to save some cash it’s better to go straight to a 350. 
 

It’s not to shit on Yamaha, there amazing bikes and never got problems with any of them but they are allot of work and bike for most off the people. The new bikes sounds different but same does the new 350. 

Restrict the airflow to the engine, and out..

Buy smaller-hole wr air-intake placed under the filterscreen. And then smaller plug in end of the exhaust muffler (also wr).

together with yamaha tuner app, more fuel and retard the engine.

I could think you could be happy with that combo.

I was a Honda dealer for 10 years, before I decided to sell and move away. I also just bought a 2023 KTM 350SXF, last June. My perspective? The Japanese appear to have said, "If it wasn't our idea? It can't be a good idea." They would rather lose sales, than follow the data of something they didn't think of first... The data says, build a 350 and you will sell every single one you build! The Japanese are still saying "Nope. Just like the dang old internet, it's a fad and someday this demand will go away." 

The 350 is an amazing machine. I never feel out powered by a 450 just stretch that cable and out  break them in the turns. 

I actually own both these bike. I have 20hrs on my 21 yz450 and only 5hrs on a low hour 22 350 I picked up this fall. The yz has a vortex done by xpr with the keefer maps. Ive actually been running the loretta's map most of the season as it doesnt have much engine braking. I feel it doesnt tire me as quick and it has a free wheel feel when coming into a corner which helps me keep my corner speed up. Now my 21 yz250f with a vortex from twisted, had much more engine braking. Its wasnt a bad thing, but was something that always stuck out to me when riding the 250f and 450 back to back. Your still going to have the 450 feel with how the bike handles. I loved my yz250f, but just wanted some extra grunt while still having that lighter bike feel, so thats why I got my 350. The 350 doesnt have as much engine breaking as my 250f.
 

If you want to go the 450 route, an aftermarket ecu will be a big help, compared to the stock tuner app. Keep the stock air filter cover as u dont want to increase air flow.... I tried a slater skins cover on my 450 and it made it more snappy down low which was good in deep dirt, but also tired me out faster and it affected how the bike cornered when I got back on the throttle.

jusg gonna throw this out there, because i have owned both, an austrian 350 already feels just as powerful as a japanese 450 LMAO. Yea, they are that good.

350s are good, really good

Yeah, I agree with Polish power. I also came off a YZ 250 F great bike just not enough motor which is where the 350 fills the gap and then some

comparing the 2025 sxf350 to both 2025 yz450 and 250. The KTM 350 chassis is not in the same league as the yamahas. Not by a long shot. The yamahas are significantly better in suspension as well.  KTM has work to do on that new chassis and the they need to give up on the suspension science experiment! 

As for the claim that the 350 has "great" power. Its quite good on firmer and dryer tracks, much better than the older 350s, BUT once your in deeper till loam or sand the 350 looses it and suddenly acts more like a big 250. It simply doesn't have the low to mid rpm torque to dive into power robbing till/sand and keep its head up like a 450.

it will never happen, you can play with the your app all you want but in reality you cant change reciprocating mass. You pull power out of a 450 and itll feel even heavier. if you want a 350 buy a 350, but ill tell you a secret. the new KX450 is an incredible blend of non abusive torque and strong top end pull. like a 350 with a little more pulling power

stop it. we know youre lying

Sorry for off topic but my best was a punk kid getting so angry with me he wanted to fight 🤪😂

I had an old street bike for sale and said I'd take a 01-06 RM250 in trade only NO other street or dirt bikes/quads. 

A kid contacts me with a 02 RM195.  Yes, 195. Sends a picture of a clapped-out black spray-painted plastics RM125 with a hideous-looking graphics kit, and no front brake line, etc.  He says I have a 195 with pro porting and jetting that will beat any 250 easily and most open bikes.  

I replied thanks but not interested in 125 as stated in my post.  He comments back with something like...I fuc*ing told you it's bored to 195 and faster are you stupid?  This thing has pro jetting and secret porting.  Nothing will touch it. 

I said I may be stupid but I'd like to see the cylinder wall of a 125 bored to a 195.  That's pure magic.

He responded with a ghetto-riddled message wanting to meet me at a place of my choice for an "ass whoopin".  He looked about 14-16 years old and weighed about 100  lbs.  

I said who are you bringing with you to do this "ass whoopin" 'cause it's not you.  

Pretty sure the OP left this thread. Seems like you could contact LASleeve and have them press in a 350 size sleeve and piston. Then work everything else out.