"Racing" CDI modules...snake oil?

[forchetto]

The weather wasn't up to much here yesterday, so instead of my usual Sunday ride I stood in my workshop with nothing much to do. You know the saying "idle bikes are the devil's workshop"?, well I set about finding something to do.

I had a look at some of my old tool relics, the sort of thing that's not used anymore, like that OHV tappet adjuster, the stroboscopic timing light used to set the timing after adjusting the old contact breakers, etc, etc.

This last item is no longer used as today's vehicles have electronic ignitions and engine management systems that can not be adjusted, so the timing is set correctly for all eternity. For those who do not know how they work they have a Xenon lamp that is made to flash in time with the spark by a sensor attached to the plug HT lead and are then pointed at the moving rotor. As the flashes are at the same frequency as the plug firing, the rotor appears to stand still and the light iluminates the index marks. You can tell the exact point at which the spark happens as the marks are visible even though the rotor is spinning. The behaviour of the advance and retard mechanism can be observed by reving the engine and watching how the index marks move about.

I then looked down at one of my pitbikes with a Honda Cub clone horizontal engine and remembered that the magneto cover can be removed without any oil loss, as the magneto runs dry. Also there are TDC and firing point marks engraved on the rotor and an index mark on the crankcase. I then ran the engine and pointed the light at the rotor and observed that the timing "F" mark and the crankcase index mark were aligned exactly. Revving the engine produced no change, same as on the original Honda Cubs where the timing was fixed on full advance. No centrifugal or vacuum advance mechanisms were fitted.

But, wait a minute, I have a fancy anodised aftermarket CDI module fitted with "Racing" written all over it and the promise of oodles of extra horsepower by, and I quote: "an agressive timing curve".

Next I made the CDI plug accessible and lined up 3 more CDI units to try out this way: The factory OEM one, an aftermarket unit with the RPM limiter removed, and another "Racing" one from a different maker to the one tested already and ran the test.

Guess what: No difference whatsoever was noted with any of them. The firing stayed at the "F" mark at idle, midrevs and high revs. How then can extra power be claimed by these units?. The overall advance can not be changed as this is set by the position of the pulser or pick-up coil. The advance curve doesn't exist as the timing appears to be fixed on full advance regardless of what unit is used.

Is this all a scam?...snake oil?...a placebo?...thousands upon thousands of these units are for sale all over the world and eagerly bought by people (me, for a start!) and we seriously believe they're doing good, maybe because we rarely test the claims and are subjective about any improvements. What do others think?.