Not necessarily young but younger:
http://www.mangago.zone/read-manga/how_sweet_is_a_sugar_daddy/
http://www.mangago.zone/read-manga/the_only_one_who_didn_t_know/
http://www.mangago.zone/read-manga/fools/
http://www.mangago.zone/read-manga/trap_ootsuki_miu/
http://www.mangago.zone/read-manga/goodbye_lilac/
http://www.mangago.zone/read-manga/neko_to_spica/
http://www.mangago.zone/read-manga/kore_ga_koi/
http://www.mangago.zone/read-manga/itou_san_kuraka_sui/
http://www.mangago.zone/read-manga/shiba_kun_to_shepherd_san/
http://www.mangago.zone/read-manga/kirei_ni_shiteyo/
http://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/
http://www.mangago.zone/read-manga/koishite_daddy/
http://www.mangago.zone/read-manga/bright_light_sprout/
http://www.mangago.zone/read-manga/oya_no_kao_ga_mite_mitai/
http://www.mangago.zone/read-manga/may_flowers_are_not_blooming_yet/
http://www.mangago.zone/read-manga/kuroneko_wa_shippo_de_amaeru/
http://www.mangago.zone/read-manga/happy_end_o_shinjiteru/
http://www.mangago.zone/read-manga/kami_sama_no_iutoori_moegi_yuu/
http://www.mangago.zone/read-manga/sado_no_otoko_o_otosu_houhou/
http://www.mangago.zone/read-manga/honey_sour_flavor/
http://www.mangago.zone/read-manga/youjin/
http://www.mangago.zone/read-manga/kyoushitsu_no_yugami/
http://www.mangago.zone/read-manga/kobi_no_kyoujin/
http://www.mangago.zone/read-manga/nichijousahan_bi_beautiful_life/
http://www.mangago.zone/read-manga/katsubou_no_manazashi/
Open for a surprise (⌒▽⌒)
Can you guys help me recommend some yaoi manga with young uke? I don't mind if it's a really big age gap as long as it's interesting