Thinking of going from a 250f to a 450f

I'd say its up to you. How often are you WFO and wishing for more power? I've ridden some of my friends 450s and there awesome, I can go way faster than on my 125. For me I felt less fatigue riding the 450 than my 125 when trying to go fast. If you don't want the front end coming up just don't twist the throttle so much. I don't have much time on 250fs though.

I just jumped from a Kawi 250F (2007) to my new KX450F (2008) a few days ago. I have only rode once and its awesome. I am literally on my way out to ride right now so when i get back ill tell you more.

So far the power is amazing, the front end comes up pretty easy but it all depends on riding style. This 450F jumps way better than my 250F.

Later

I am about 230lbs and ride a 2005 CRF450R. They do have a ton of power but you can tame it and make it more manageable. For example, you can run a gear higer (i.e. instead of on the gas in 3rd, lug around in 4th) and that will tame it quite a bit. Also, for me it is a confidence builder. On the 450, you can pretty much clear most jumps out there whereas on a 250f at 230lbs you may need a little more technique and carry more speed to do so. It's just nice to know you have more than enough bike when hitting that big jump for the first time. Also, I beleive the longetivity of the 450 is better than the 250. I rarely ring my 450 out whereas when I have ridden a 250f I am winding it out much more than my 450. When I am tired on the 450, I pull off. That is the one drawback in my opinion...on blip at the wrong time and you can get into some pretty good trouble. Good luck.

i would say that starting with the smaller bike will make you a better rider faster. that may not carry much value coming from someone who started on a two stroke two fifty, but after i bought my bike i later read that its best to start small and get the most out of your bike before you upgrade. my 2 cents for your consideration

For your size a 450 is managable. I'm only 125lbs and I can pull similar lap times on my friends 450.

go with the 450
I am 6'0 250 and I went from a KTM 125 to the same bike you are looking at (2003 crf450r) and it is like night and day.
You are big enough so that the front end will not want to lift up as much compared to a guy thats 5'10'' 130. And as stated previously, if the bike has too much power, shift up a gear.
I am completely satisified with my switch, and I think you will be too.

Yeah man Id go with the 450 for sure. Just respect how much power it has at first and take it easy. Once you get used to the bike you'll rip. Especially coming off a 250f because you have to keep momentum up and ride smooth to go fast on those, so if you ride like that on the 450 you will fly. Only downside is that you cant play around/whip it over jumps as much because it does feel a lot heavier. Arm pump isn't an issue for me. In my opinion, it takes a lot to get tired and worn out on a 450 because its super easy to ride. And when you do get tired and make mistakes I find the 450 much more forgiving because unlike a 250f, you have the power to correct yourself in pretty much every situation.

If you do go with the 03 CRF, change the cam chain tensioner to the newer style (04-up 450/250). The 02-03s had the tensioner with the phillips head screw and they were known to fail and allow the cam chain to slack and mess up timing and occasionally an engine, the newer models use a hex bolt (8mm head).

Honda Part #15420-MEN-671 $43.11 through ServiceHonda.com