I recommend "Window to Window", but sorry it doesn't have more than 100 chapters... but it's extremely good!
"Akai Ito No Shikkou Yuuyo" is not long but very good!
"Sick" and "Caramel Honey" are not long but good!
"Kyou Kara Omega ni Narimashita" is beautiful but not long.
"Let's Have a Baby Dragon" has 95 chapters, it's close...
"Takkun to Stalker Danshi - Kyou wa Takkun no Tissue o Tabemashita" is good but not long.
"BL Motel" has 92 chapters.
"Royal Fiancé" is good but not long.
"My Darling Signed In" has more than 100 chapters!!! (≧∀≦) finally found one! Unless you read it already ╥﹏╥
"Ookami-san to Eroi koto" is legendary!!! but not long.
"Idol-kun wa Koi wo Shiranai" is good! not long though.
"Can't take my eyes off you" is good! but not long.
"Smell Fetish" is good! but not long. （/TДT)/
"Kiraide Isasete" is gold! but not long. （￣へ￣）
"Sayonara Alpha" is good! but it's yet another not long one.
"Sexual harassment brothers" is good....(▰˘◡˘▰)
"Ore no Otouto no Honjitsu no Onedari" is good too....(▰˘◡˘▰)
"Ten Count" is good!!!
"Terebi-kun No Kimochi" is awesome!!! and cute!!!
You HAVE to read "Bokura wa Nando mo Koi o suru"
Can any one recommend me a full colour bl with more than 100 chapters (⊙…⊙ )