21-23 VS 24-25 YZ250F, Is newer really better?

Newer is always better. Only thing better than a new bike is a new girl friend 

Not a perfect comparison as I primarily race off-road, but I had a 2021 250FX, and a 2023 250FX. I have a 2024 YZ250F this year and think it is an improvement, once you work out the god awful stock mapping. 

I've been running the Stevie map from Yamaha, and it has been the biggest improvement for the loss of bottom end as compared to the previous generation. I've tried about a dozen or so to get to this point, some are better and some are worse (Sorry Keefer). 

The bike turns infinitely better than the previous generation. It feels more nimble and responsive, especially in tighter corners. This alone makes it an overall better bike, as I struggled occasionally with this on the old bike. 

I don't feel like the bike has become too unstable because of this either, I just think the old bike was TOO stable. 

Reliability has been good, I got the bike hot at an off-road race and had to replace the head gasket, but no other major internal wear. I'm at 45 hours, so I did a top end anyway. The piston looked brand new. 

I don't own the new one but I do think it's going to come down to preference and where you ride. I have been drawn to the YZFs because of the quick rev and instant response, along with the stability and ease of set up. All of those traits have been slightly altered on the new one. Would it keep me from buying one? Absolutely not. But I did not have a problem with the handling of the 21-23 bike. And I really appreciate the stability of it, with the rough tracks that are around here. I think the 21-23 really all comes together to give the bike a riding style where you can be aggressive with the throttle and point it where you want it to go. It just goes like crazy, with no drama, and I love that about that bike. The response and stability all seem to go hand in hand with that type of riding. But I think the new one seems to maintain enough of that character but also have more appeal to front bias riding style, along with ergos that seem to more "normal." 

To answer your question, is the upgraded needed for a current 21-23 rider, I honestly don't think so. I'm dialed in with a dual injector and still pretty low hour, so I don't sweat the upgrade. But once it's new bike time, I think it's still at the top of my list. And I think this new one has a better chance of pulling someone away from another brand, than the old one did. But I don't think the new one is going to feel like a must-do upgrade for riders already on blue who love the 21-23.

I like the 23 better than the 24 but the 25 is a big enough difference that I think I'm gonna have to have one. First I have to stop throwing money at my KLX 140 project though. BTW - There is an airbox mod you can do on the 24 that did make a decent difference on the 23 and 24. It'svjust trimming some plastic.