The KMX 125 and 200 do not have shims in the powervalve and they are not adjustable . To raise the output remove the collar from inside the exhaust where it joins the barrel or buy and aftermarket exhaust....
Looking for a 125 but not sure to buy, well the short answer is the Honda CBR125 but if you want a few other options read on. What type of bike is the first, they all have different styles they are in general ...