Since this post has been reborn, some clarifications are warranted for those reading later.
Reactions of sodium thiosulfate and chlorine are pH dependent. With reactions at pH's less than 8.9 and greater than 6, the dominant aqueous chlorine species is ClO- and there are the following two possible reactions:
The dominant reaction: S2O32- + 4ClO- + H2O ---> 4Cl- + 2H+ 2SO42-
The minor reaction: 2S2O2- + ClO- +H20 ---> Cl- + 2HO- + S4O62-
There are several other possible reactions at lower pH's. Note in the dominant reaction that acidic hydrogen is generated and in the minor reaction basic hydroxide is generated. More than likely the minor reaction starts taking more precedence as the solution approaches higher pH's. For most neutralizations around pH 7, I use 4 mole Cl(-) per 1 mole S2O3(2-) from the dominant reaction. You can always just use 2:1 and spend more money. In practicality, one may have to add a little thiosulfate using 4:1 since there are two viable reactions that actually occur. In other words, as the neutralization proceeds through the primary reaction, the minor reaction starts coming into play. This is governed theoretically by the activity of the reagents and products.