NOTE: This kit for the KOKUSAN crank model RSV4s. See our other kit for MITSUBISHI crank RSV4s.


This is BDK's complete race generator kit including the lightweight flywheel, stator, mounting plate, cup fasteners, connectors and specific regulator / rectifier.

Significantly lighter than standard, offering higher output than 'race kit' versions, providing increased throttle response,less gyroscopic forces and more bhp everywhere.  It is designed to fit high performance injection engines, and as a replacement for standard alternator systems.

Typical gains on a standard bike are around 5-6bhp.

With fuel injected bikes the option to run a 'total loss' system has become impossible, due to the drains from fuel pumps and injectors.  The standard alternators are designed to run headlights etc and need to be able to supply significantly more power than you will ever need on a race bike.  This means you can use a considerably smaller system, reducing the weight of the crankshaft assembly.  

Most race kit generators have a smaller rotor with less windings in the stator so that they produce less outright power (and accordingly take less power from the crank to generate the electricity), and use a standard reg/rec.

The problem with this is that you have to rev the engine quite hard to produce any useable power and any excess electricity created is still converted to heat in the reg/rec and thrown out the back of the bike.

Our generators also use a small rotor but our windings have a lot of turns of fine wire.  This allows us to provide strong and consistent power at lower revs, but the clever part is in the reg/rec.  The reg/rec contains a switching system which cuts the generating power when the desired voltage is reached and therefore the power is not taken from the crank to convert to electricity in the first place.  This is why our reg/recs run much cooler than standard models and why you cannot use our generators with a standard reg/rec as the generator would be under load all the time creating excessive heat in the windings.

This state-of-the-art alternator uses a tiny 45mm diameter rotor weighing only 198g.  This significantly reduces the effective weight of the crank by not only reducing the weight of the rotor by over 67% but also by reducing the radius over which this weight acts.  Standard rotors are around 120mm in diameter (compared to ours at 45mm), so the speed of the edge of the rotor is much higher - for example at 14000 rpm the standard rotor edge is travelling at 200mph, our rotor edge is only travelling at under 75mph.  Anyone who's tried knows that it's a lt takes significantly less time and effort to accelerate up to and stop from 75mph than it does a vehicle 3 times the weight from 200mph; this translates to much improved throttle response and faster acceleration.


When there are no items in stock then typical lead time for this kit is 3-4 weeks.