I still ride a '90 CR500. Adding a flywheel weight would be a bonus, I rode an '86 KX500 before this and a YZ465 before that. This CR500 will quit if you lug it down unlike the others. The YZ465 was a tractor in the woods and you couldn't make that thing quit if you tried, 3rd gear at almost no RPMs and it would keep on going! My KX500 had a Moose weight and it was very manorable in the woods because of it. Also keep in mind that Honda doesn't use an exhaust valve in their 500's, this sacrifices a litle low end and moves it to the mid range, like as if you will ever miss it! The original write-up says "would you believe clutching a 500 at low end?". The CR500 will tend to surprise you when it hits if you're not ready for it. The inverted forks are definately the way to go, just point, steer, and gas it! My KX with conventional forks always felt like it was fighting you. Turning the bars in a hard turn on the KX was merely a suggestion to the bike that you might want to turn, the flex in the forks was a weird feeling. Ultimately, that was the reason that I got rid of it. I always describe riding my CR500 like trying to ride something that doesn't want to be ridden, or trying to control something that is out of control. The power of these big bores will amaze you! Don't let the nay sayers change your mind with the "why would anyone want to ride one of those things in the woods", trust me they are what you want. No run necessary, last minuite decisions are easy, roost or wheelie on demand! I still have the original magazine write-up on the '90 CR500 if you're interested.
There is no replacement for displacement!