How to select right BMS ?
Well its great you want to make battery pack by yourself. But I would suggest not to do so until unless you have correct information about the working environment of lithium cell and it chemistry. If still you want to proceed, here are the things you should take care while making one.
If you want to replace your LA battery of your motor bike, then 12.8V 6Ah would be work properly. Considering your current requirement for can select 1200mAh or directly 6000mAh cell. If using 1200mAh cell you have to make cell connections in parallel to make up-to 6Ah as below.
There is one way to figure out how to select BMS. Before choosing BMS we must be aware of the current consumed by the self starter circuit of the bike. It (bike starter) will take some peak current to start the bike which is to be considered before choosing BMS (want to know how to measure current, click here). Suppose if it take 70Amps then we must select a BMS which allows peak current of this value.
The second way (not recommended) is to by-pass BMS logic which cuts off the rapid flow of current protecting the cells. And only using the balancing circuit of the BMS to balance lifepo4 cells.
Hope you got your answer. If have any query comment below your question.