Does Honda SP 125 have ABS or not?

Me too sometimes face this. It happens generally from third to second gear. But I think it's not a problem , I assume when you are not at a specific level that gear should be changed, it won't change. Slow a little bit extra & it will change. As you might have observed that you can ride 25kmph in 5th gear without any problem.

0.9ltr 10W30

It depends on you , i travel solo 180 km in uttarakhand= Kashipur — Ramnagar — Haldwani —Lal kuan— Rudrapur — Kashipur. i only take a small brake in Lal Kuan for about 20 minutes. although i ride continuously Non Stop. i also travel from this bike from = Kashipur -kala dhungi- Nainital ( take shortcut for Nanital from kala dhungi) it around 87 km the hills region. with a pillion. most of the time in hilly regions, i ride in second or third gear . it take some more power because of pillion, otherwise in solo ride to Nainital it runs smoothly like regular bike 100cc bike on mountain afterall its engine is 125cc ( this condition is only with pillion on mountain). after all it is good bike . The only cons i have see in it is the seat cushions, it make pain in long ride