Cut Prim Indicators Kit

Take one of these prims and link it to the back of your bike running KCP ACS v4+

The problem with adding indicators/turn signal lights is the amount of prims they require for separate light surfaces. Here's one workaround in one standard prim that gives you indicators for your bike running ACS v4+.
You will need to get creative! Strech, warp, and adjust the parameters of these prims. These cut prims use inside faces to give you two separate signal lamp surfaces.
You can apply any textures or colors to the prims you desire. Set the non-light face(s) to transparent and float the lenses above your sculpted indicators, or incorporate the full visible prim into the design of the bike.

You can of course use the normal Turning Indicators scripts for individual sculpted prims.