What did you learn after getting your first 450?

The definition of torque.

3rd gear starts, and concussions.

How much easier it is to go alot faster.

They are great bikes and people that complain about them are mental.

Respect it before it makes you respect it.

Shift up, don't over ride it, relax and be smooth. Apex the flat corners.

That it was a lot easier to ride than my KX500s were, and basically just as fast. 

If you have bad technique, a 450 makes it that much more apparent.

To up my workout on the rowing machine... due to exactly what you described.

I wish I could remember, I still have a headache from perris 2007

The very first time I rode a 450 ( was also my first on a 4 stroke) I ended up separating my shoulder and also suffering a good concussion.

I was rolling around the track on this brand new CR450  just getting a feel for it when I came up to a big step up that I've jumped a few hundred times on a 250 2T......well, I rolled the throttle open and went sailing over the step up with ease, that is until I rolled the throttle closed in the air. The fucking bike rotated so quickly and I was head first over the bars...I've been scared of the things ever since. 

first was a RMZ450 05, I remember that it never seemed to sign off the top of the powerband like a 250 2t, , they just kept pulling, 

‘04 CRF450R.  Felt like a cheater bike. Unbelievable torque, super fun to ride.  Killed it on the starts.  
This is coming off a 2002 RM250 that I loved to ride (other than when it tried to kill me)  🤷‍♂️

Yup...I found out the hard way.

I learned that it wasn't wise to ride them like 2 strokes. They push back.

2018 KTM450.

Great bike, easy to ride, fastest I’ve ever been. Then out of nowhere it would bite and bite very hard, sold it and went back to a 2 stroke.

I learned I’m an idiot for thinking I’d be better off than on my 350. Traded it two weeks later on another 350. 

I learned that I’m a 2 stroke guy… 🤣

Bingo. Felt like cheating. I didn't ride for 10yrs. During that decade, 4-strokes emerged. When I started riding again, I bought a 250 2-stroke. Curiosity finally got to me and I said, let me try one of these fancy 4-strokes. My buddy had an 2007 CRF450. My jaw dropped. I just remember the rear tire hooking up everywhere and the frightening acceleration. I loaded up my 250 and stopped at the local dealer on my way home and bought a brand new 450. LoL true story. I want nothing to do with a 450 now

What I've learned. It's always in a hurry and gets to the place we're going before i'm ready and or prepared to get there.

I learned that it was time to sell my 250f and never own one again..😆

After years of wasting money to make a 250f faster, getting a YZ450Fx and retarding the timing a bit was all it needed. So ridable, 450's make good trail bikes because the torque.

08 YZ450F, was a great bike after a few small mods.

It made me lazy.  They can lull you into being complacent, then bite you after it has worn you out. 

The first thing I learned after getting my first 450 was...I really don't need a 450. 

It got wayyy easier to hit jumps

I learned that my first 450 was not a good bike for me. An 05 crf. I couldn't do a lap without stalling. My second 450 was an 07 yz. Good bike a bit fast for me and difficult to turn. My last 450 was an 09 yz. Best 450 for me. Slow for a 450. Much slower then the 07. But just right for me. 

I've never owned a 450, but I've ridden a few. I learned that they're heavy, ill-handling, hot (burned the shit out of my boots and pants just putting it back on the stand,) and stall easily. Also, they want to throw you over the handlebars, like Boomslang said. Finally, they make mid-pack novices as fast as national intermediates overnight, contributing to more injuries than I've ever seen in the sport.

I did own a 250F and I learned how to kick it 10 times, then get back off and do a rain dance, then sacrifice the bones of a chicken, kick four more times, then half a kick to get to TDC, release the compression lever, pull the hot start, say a final prayer, then kick and hope in vain that it fires up. Only had to do that two or three times and it usually did, unless I was in the middle of a race or some other scenario when it was vitally important to get the thing going. Heaven forbid you were ever stuck on the train tracks on one.  No thanks. 

Even after many years of improvements, a 4-stroke motorcycle is still a major compromise and disadvantage for me. Anyone who somehow thinks they are better is mental. (😉- right, AssangeMX?) 

EDIT: Perfect time for a grammar lesson! Here's where past-perfect tense makes more sense. I remember many people trying to understand the difference between "did something" (past tense) and "have done something" (past-perfect tense). My very first sentence was, "I never owned a 450, but I rode a few." I have changed it to "I've never owned a 450, but I've ridden a few" for more precise meaning. The former implies somewhat that I may be done riding altogether, or that I'm speaking about a very specific time frame. My edited, more correct statement means something more like, "as of right now, I have never owned a 450. The future may be open to interpretation." Even though I feel like I never will own a 450, it is more accurate to describe my meaning as "I never have," rather than "I never did." 
Sorry for the momentary hijack. Now back to your regularly-scheduled programming. 

They are just plain "more" than a 250 two stroke in every way.

My first Race 4 stroke was a 2000 yzf426 - Don't chop the throttle off a jump.