I am new to the Gassers. Disregard whatever I say if you think it's not relevent. You won't hurt my feelings. Especially if you don't tell me you disregarded my feelings.
I have put flywheel weights on almost every bike I've ridden off road. From a KX 125, to a KDX 200, to a KX500, to a CR 480, to a KTM 520, to a CRF 250X, to a GG 250 XC. I like power, but controllable power. I ain't good enough to blast away on a crazy powerful bike on wet rocks and roots, or even on a road. Consider that your bike's top speed with a flywheel wt will be exactly the same as without one. Maybe even faster with one if it keeps you from crashing.
Seriously, you probably won't notice much difference in mid range-top rev. You will only notice it from idle to the beginning of the midrange pull, on any bike that is likely what you will feel.
99.999% of us ain't real good riders. We pay to ride, not get paid to ride. Some of us may be pretty good compared to some other of us. But we ain't getting paid to ride, or we would not be wasting our time here on this website. We would be practicing, riding, racing, working on bike setup with our team, riding in a race truck headed back from a big race, or smoking weed trying to come down and relax and deal with all the stress of the aforementioned stuff. Or talking to our investment guy about how to get ahead in this shytty market. We'd be: "Somewhere other than here". I think that was a song lyric from the 70s. Or we'd be telling our mechanic we want to try a 2oz heavier or lighter flywheel wt in practice, and he'll be quietly mentally bitching about having to turn one down by 2oz on a lathe or add a slightly bigger one.
Flywheel weights just slow things down a little. Not much, but a little. Bigger ones= more than a little, but not much more than a little. Only a little more than a little. No, I ain't smoking. Don't need to, I already have a flywheel weight.
You can buy flywheelweights from Steahly or Trailtech, probably somewhere else too, in 4-12oz sizes for many bikes for 100.00 or less. That's approx. ONEHUNDRED, new retail price.
You can have almost any machine shop turn one down, (not tell the fat party gurl she's fat and you can't do her), for about 50.00, to whatever weight you want to try next.
You DO NOT LOSE ANY POWER WITH A FLYWHEEL WEIGHT! Your power is exactly the same amount, just delivered differently. Generally, if you are an average Joe rider, or even a pretty good Joerider, you won't notice much difference when half-full throttle. You will notice when you are going slow, technical terrain, transitions to different terrain at slow speed, you are tired, etc. the ol gurl will be just a tad easier to ride at slow speeds only. Not much difference when you are pounding away at her.
Flywheel wts can cover up other issues such as poor jetting, wrong pipe/silencer/setup/gearing/rider/whatever issues. With or without a flywheel wt, you need to do the fundamental bike setup stuff. But a flywhlwt will rarely hurt any riders speed that is under a well trained A+ rider, and most of those guys are using one if they need to. It may be only 2oz for their taste, or 20oz, since their pro mechanics can make/modify it to whatever they like.
On a 200, 6oz will be noticeable. 8oz will jump out a little. 10-12 will really make a change. It's 100.00 from Steahly, and if you don't like it, you can sell it on here, or ebay for 50-75.00. They can be added or taken off in 15 minutes. It's the cheapest thing you can do to your bike other than trying a different tire or changing your graphics to go faster. Remember, graphics make your bike faster, flywheel wts only make your bike smoother so YOU can ride it faster.
I have a 12oz Steahly, it's probably my 10th one on 10 different bikes, and I told them I'd advertise for them. But I ain't lying, just bragging on the product.
"I am a non-Lawyer, non-compensated spokesperson".
Almost forgot, the larger PV covers really do change power characteristics, even more than a flywheel wt, allthough I doubt a PV cover change will affect stalling issues. It will change power delivery. More bottom, a little less top end. I have both a larger PV cover and 12oz. flywheel wt on my 01 XC, and other mods. It's like a big easy to ride 4 stroker with the light wt of a 2 stroke, and the lower maintenance costs.