Oh come on, it's
NOT just weight,
otherwise you'd jst get a 2stroke
Like a Max 125cc evo senior, 26lbs, 30hp @ 12000 rpms
or an AixRo XR50 (same weight as the stock gx200 but 44hhp and 11k rpms
and both are actually way cheaper than what Mammoth for example put in his gx390 so far
I think it's perfectly legit to throw money at a
stupid engine design to see what can be done with it.
especially when it comes to racing these (one must obey the rules of course)
But you must admit the "rules" for these engines came from the simple fact that they were cheaper than proper kart engines
and to allow for "less money spend" classes it was adapted and became popular since they were literaally everywhere anyways.
And then the "oh but i can throw more money in" guys came along and THIS is now the result.
But that doesn't make it a particularly good engine design for anything but reliabilty (if untampered with)
it just happen to be the "standard go to" because of el-cheapo kart racing
'sid
PS those horizontal cylinder 140cc Hondas for example are not just as popular with modding yet.. but pumped to 190cc they still have 10k rpm ~20hp an overhead cam five sequential gears and the same weight as a stock GX240 and cost next to nothing as a clone too

if one puts a modded head and custom cam, forged flat top piston etc to one of those.. I wonder what would happen