I have an Iame Easykart 100 with some funky revving issues. When it starts getting into high RPMs it will choke and hold there and stutter and after enough time it will either finally break the barrier and reach full RPMs or just stay stuck at high mids/low highs until slowing down and trying it again. I’m not sure of the bore/piston sizes, but they look in fine condition, as well as the rings. I just replaced the cylinder base gasket, exhaust gasket, got an entirely new carburetor, and the ignition coil I had replaced before putting into storage for the last 2 years. It has a Tillotson HL-384A carburetor with adjustable low speed mixture screw that I’ve been trying to tune just right and a fixed high speed jet so I just don’t understand what could be making it choke in high RPMs. If it’s any help I live in florida so it’s quite humid.
It could just be too rich on the main jet, or the inlet needle in the carb is leaking and allowing too much fuel to pass.
Has the carb been rebuilt?
Wellll good and bad news
After getting the low end mixture just right, and running it down my street and back a dozen times, it managed to break through and fix itself on like the 6th go, and after that revving normally all the way through for the rest of the time. Bad news is I’ve created this post for no reason and wasted your time apparently. I’ll continue to drive it more later today to make sure the issue doesn’t come back, but it was probably just a matter of me not properly warming it up and actually driving it for enough time to truly examine the problem. Thank you for your help and sorry again.
Sounds more good news to me 
Yeah they won’t take kindly to tootling around and will behave strangely. Do you have a track nearby?
Yeah that’s the thing is my track is about an hour and a half away so it’s a bit hard to test things out and see what needs fixing before taking it up for a full track day. Even had a cranky old man chase me down in his car and eventually called the cops on me for driving it down my small street and back in the private gated neighborhood I live in… but at least I can say it was running pretty smoothly while I was trying to lose him
Probably the first time he saw a kart go that fast, my neighbors are SUPER cranky too, the HOA keeps telling us the trim our palm trees and whatnot. It’s honestly hilarious
Be safe, get that thing to a track. Things can turn really ugly, really fast on the streets.