350 vs 250f With Mods

Big bore kits on 250fs can really make quite a difference. Nothing like a 350 I'm sure but they can make a 250f way more friendly to ride. I have an 07 with a 290 jug that I ride when the conditions are really bad and the torque increase is obvious. When conditions are normal I just ride a mildly modded 20 250f and when they are really good it's 250 two stroke time!

It looks like I did the opposite of a good majority of the guys replying here. I had a 2020 yz250f that I loved. I had a PC pipe, Twin Air intake, and a few other small mods. I was always searching for a little more power and snap. (I'm 6' 175 pounds, former A rider)

I now ride a 2022 MC350 and love it. I have an RM250 and RM125 for when I want to play, but the 350 is the greatest all around bike I have owned to date (aside from maybe the 08 CRF450R). I have the Twin-Air intake, Akrapovik slip on, KTM map switch, 1 tooth dropped from the rear sprocket, and a Twisted tune Vortex. Its snappy and fast, but not in the way a 450 is. Its more like a 250f that's modded to the point of blowing up!

I didn't slack on suspension either since the KYB is just so good on the Yamaha. I have cones up front and an Ohlins on the rear.

The Conevalves are good.   I really like those forks for pushing hard.   What do you think of them?   I haven’t heard of too many people going Ohlins for the shock and WP for the fork…..how’s the combo?

I was originally going to go with a Traxx shock but found way too good of a deal to pass up. I think that the Ohlins works really well with the cone fork. I think its all just a matter of getting the pair tuned to work well for how you ride. This is an all around impressive bike. 

If the Austrian bikes aren’t working for you, get the 250F. The more comfortable you are woth your bike the faster you’ll ride it. Anyone pretty much any size can be competitive on a 125 in the C class, the 250 will be fine.

If you’re open minded, have a look at the TM 300 4 stroke. Great for tall riders and has the power of a true national caliber works 250F at a much cheaper buy-in and with normal maintenance cycles.

This just enforces.. more and more... the frustration with the big mfg'ers that don't build a 350. I ride a 16 KTM 350XCF and a YZ250FX (2020) with a 270 kit and cams. At least have access to them..... If Yamaha made a YZ300FX... YZ350FX... I'd sell both in a heart beat and get one. 

I enjoy riding the FX more then the KTM. FX is more playful... turns better. I like the FX chassis traits better.

Athena makes a 283 bb kit for the FX... I may swap out the 270 cc kit for that one. Just a little more then it has now would be ideal. 

I guess were stuck building what we want... vs the product managers paying attention and building what the customers want. This is an area KTM has done really well in with the various models they make.  

Oh well.....So the story goes. 

try raptor pegs with the 10mm lower and 10mm back offset, higher bar mounts (ktm powerparts phds +10mm) and a high seat +20mm on the ktm.. makes a huge difference.

YZF ergos are not as good in my opinion but maybe it is with the same changes as above. Had a yzf450 -22 but didnt like it compared to the ktms.

I 100% agree with this.

No offense to the OP but at the skill level he's describing I highly doubt the jump down to a 250F will effect his lap times at all.

That is a valid point, I think that most people never need more than a 250f for their capabilities. They aren't that hard to maintain these days and last a while under the abuse most people can offer them as long as they are maintained.