Need for Spark Advance?

[Gene Ungar]

I'm early in the restoration of a '76 Kawasaki KH500 triple, the last of the widowmakers.  The KH500 has an electronic ignition.  It's quite clever, using 3 pips on the crank to trigger a sensor that is attached to a brain box.  A distributor commutator ring on the alternator sends the ignition signal from the brain box to the correct (of three) coils.

The brain box changes the ignition advance, firing the spark more retarded at low RPM and more advanced at high RPM.  So this contrasts with how the RDs do business.  A fixed spark at 2.0 mm (or 1.8 mm with modern gas) before TDC regardless of RPM.  The RDs run quite well over a large RPM range.

Both are piston port engines.  Any idea why Kawasaki went to the additional trouble of incorporating an advance?  Just curious.

[m in sc]

was a crap design in that regard.

I fit an H1e 2 pickup igntion to an S2 i had, used a zeeltronic controller on there (the vcd04, rd unit, not the triples one) and programmed a proper curve. made a HUGE difference.  or, contact jim hobbs at lakeland services for a replacement box.

h1 was never considered a "widow-maker" btw, that was the h2   

[m in sc]

i tried the '11' unit, didnt work well at all.

that setup with -zero porting or head-work- and s3 carbs, dencos,  and k&n filters & on 2" runners put down 59HP at the wheel. I give a LOT of credit to the ignition curve.

also note your base curve has to compensate for the cdi's 4k and above advance. so the curve looks funky plotted out.

[waktaylor]

I installed the VAPE CDI on my rd400 and the difference from fixed points was unreal but completely expected since almost every ICE has variable timing. in my case I think I gained some from aged "condesor" that was causing some misfiring.

Timing curve is well worth the effort.