if you have not changed its oil change the oil
25-30km/h not much difference and i think 70cc
small engine will ask for gears quickly even cg 125
at 40km/h in 3rd feel heavy and asks for 4th gear
although it max 90km/h in 3rd gear
so these small cc bikes ask for gear. Only bike that i rode
and don't asks for gear quickly is yamaha ybr and i guess
its because of its latest tech smooth engine
just enjoy the bike hopefully it will free by time as still engine is new
and i suggest you not to go for any tuning before 5000km enjoy the
bike at factory settings just lube the chain & adjustment if requires
and oil changes on time