India started the day's procedings in a positive note with a 42-run opening stand between Shreevats Goswami and Abhinav Mukund.
But then India's top order collapsed as three wickets fell in a span of just seven runs.
However, the arrival of Tiwary gave the middle order some sort of semblance as he along with Virat Kohli put on a 50-run stand for the fourth wicket to resurrect India's position.
Tiwary was more severe in his approach hitting five sixes and five fours in his knock of 86. After Kohli's departure, he along with Iqbal Abdullah, added 58 runs for the sixth-wicket.
India were finally dismissed for 199 in the last over of their innings. The Bangladeshi opening bowling pair of Rubel Hussain and Golam Kibria both took three wickets apiece.
Bangladesh may have fancied their chances at the start of their innings, but all their effort went up in smokes as Indian seamer Abu Nechim struck with venom.
Nechim scalped six wickets for mere nine runs as Bangladesh were dismissed for just 70 runs. Amanpreet Singh picked up two wickets, including the prize scalp of Mahmudul Aziz, the Bangladesh captain, for 17.
For the host Nasir Hossain, who scored 21, and Aziz were the only batsmen to register double-figures as India made good use of the bowling friendly conditions at the Colts Cricket Club ground.
Result: India U-19 199 all out in 50 overs (S Tiwari 86, Kohli 24; Rubel Hussain 3 for 34, Golam Kibira 3 for 42) beat Bangladesh 70 all out (Nasir Hossain 21, Aziz 15; Abu Nechim 6 for 9, Amanpreet Singh 3 for 17) by 129 runs.