Kymco mongoose 90 loss of power.
The exhaust might be plugged. Try removing the muffler (or maybe just the spark arrestor) A four stroke really should not carbon up the plug like that. My best guess would be the clogged muffler. It might have a bolt at the end of the muffler. If it does, remove that and pull out the spark arrestor first. If that does not help, remove the muffler from the pipe and try it. (obviously, it will be loud when you do that) Although it is possible, I doubt compression is the problem in such a new machine.