KX flywheel

What mods do you have so far? The 220 doesn't have much "snap" untill you do some decently serious stuff to it. A light flywheel would probably just make it harder to ride.

A flywheel is a serious mod. Changing the rear sprocket to a 50T or maybe a FMF woods pipe or getting it jetted right isn't and has more impact on the bike ....more than any other mod out there.

If you wanted a MX bike... you shoulda bought one.

It's false, the ports and port timing are completly different. Runs far less compression as well. Might as well be 100% different from a KX. It's just not made to be a "fast" motorcycle. A desert pipe would be a better choice than the woods if you are looking for more power. Are you running an aftermarket silencer as well? A bored out carb and some porting / head work will help as well.

My bike has been ported, head decked and reshaped, and the carb bored out my FRP. I run Boyseen reeds, an FMF Desert pipe w/ a Turbine Core 2, hacked up airbox lid, and proper jetting. Back-to-back with my co-worker's stock 220 mine is an animal, absolutly ripping in acceleration compared to him, and reving to the moon to boot. But compared to any stock motorcrosser mine is a dog.

I don't think a lighter flywheel would be any benifit to it at all. The stocker isn't unusually heavy, and going lighter will make the bike seem to suffer lowend and be more difficult to ride overall. I would give you a suggestion on the best bang-for-your-buck mod, but I did all mine at once over last winter, so I can't say which mod made what difference.

I feel like I am in the same boat as you. I bought my bike because it was a real good deal, then spent an arse load of money on it trying to make it what I really wanted. It's great fun on the tight single track trails, but everywhere else it leaves me craving much more performance engine/suspension wise. I hate it when I jump on one of my buddy's stock MX bikes and feel 3 times faster than on my bike that I put well over $1000 into. If I can make myself save some damn money I'll be getting a motocrosser for a 2nd bike this winter.

I've owned a KDX and many MX bikes, and frankly for MX use you are much better off selling it and getting a MX bike IMHO. I love KDX's but they simply don't work well for MX. The chassie is all wrong for it. Too short, too much flex, not very stable, too heavy etc. The KDX is an awsome bike, I loved mine dearly, but even once you get the motor running really well, the chassie will be a major hangup for MX. You can ride MX on the KDX, I've done everything but the "big gulp" (uphill double where Henery broke his arms when his YZ seized) on the Budds Creek MX track on a stock 200, but its much easier and more forgiving on a MX bike. If you mis the downramp on a large jump on a KDX its probably going to hurt a lot while MX bike will be much more forgiving. If you can have a dedicated bike for woods and MX that's great, if not a MX bike with some cheep mods does a much better job trails than a KDX can do on a track. Right now my main ride is a CR250R with some minor suspenson work (stock valving, just different comp springs in the forks) and guards and I'm happy with it in the woods or on the track.

If you do decide to put more into the KDX I'd suggest a bigger carb and porting. The 220 has a tiny carb and super mild ports, even smaller and more mild than the 200. Bolt on's (like reeds) just aren't going to change that.

As for the lineage of the KDX200/220 mill, I'd have to say that the top end is unique to the KDX while the botom end borrows heavily from an older, cylinder reed KX125. The stroke is longer than the 125, but not by a huge amount. Externally, the cases look almost identicle.

good luck