The VS1400 years 1996-2008 use the same $900 igniter assembly (OEM Igniter Assembly part #32900-38B50) instead of a capacitor discharge ignition (CDI).
A good aftermarket igniter box for those years is the $228 Dynatek 3000 Series Ignition D3K32. http://www.amzn.com/B0022Y0ZWK/
The only real way to test your CDI or igniter box is to swap it out with a working one of the same year/make/model. However other electrical components should be tested first as one of them is more likely to be the problem.
The Capacitor Discharge Ignition (CDI) or Igniter System
Black box, brain box, pulse pack, igniter box, CDI module, power pack, whatever you want to call it: if your motorcycle is newer than 1980, it probably has a black rectangle spouting wires under the seat that makes the magic happen. For the VS1400 the OEM part is the Igniter Assembly part #32900-38B50 for years 1996-2008.
What is CDI? What does a CDI box do?
What Does a CDI Box Do?
What Does an Ignition Coil Do?
What Are the Signs of a Failing Ignition Coil?
IGNITION SYSTEM DESCRIPTION (VS1400 Service Manual pp 18
The fully transistorized ignition system consists of a signal generator, ignitor, ignition coil and spark plug.
• The signal generator comprises one rotor tip and two pick - up coils .
• The signal generator coil is mounted on the generator cover.
• The output of the signal generator goes to the ignitor unit where it turns the transistor ON and OFF alternately.
• As the transistor in the ignitor unit is turned ON OFF, the current passing through the primary windings of the ignition coil is also turned ON and OFF accordingly. This induces the secondary current in the ignition coil secondary windings and produces the spark between spark plug gap.