The Crane HI-4 ignition system comes in several
different variations. The original HI-4 modules replaced the ignition sensor located
inside the camshaft nose cone and required some rewiring of the bike. This unit was
available as a 50 states, emissions legal unit and the 'race only' unit. The most recently
released unit (HI-4E) replaces the stock HD ignition module, requiring only that it be
plugged into the stock wiring harness.
While Bike Tech does not have before and after
comparisons for the stock HD module vs. the HI-4 module(s), it does have experience with
the original HI-4 race module. Many of the features of the HI-4 are much more important on
high-compression, high horsepower bikes than would be on a stock bike or one with a mild
cam (EV-13 or Fireball 300). The variable adjustment for the advance curve allows you to
tune the bike to just below the point of detonation in the mid-range power band.
The ability to vary the rear cylinder timing can
result in several horsepower difference on high power bikes. Making this adjustment is
tedious and time consuming since the expected adjustment figure will be less than a degree
of timing. From experience, 1/2 degree of timing adjustment on the rear cylinder is a