For over 10 years I used Sparx exclusively. Sold and installed nearly 40 units.
In all that time, one client had (2) rotor/stator failures, and I believe his black box failed. Another client send me back his black box non-working, it was replaced in warranty. I had one that seemed dodgy and got a free replacement.
So, total of 3 out of 40 Sparx units failed, with one unit having 3 failures on same bike. In retrospect, that's on the high side.
That's some good data: 10yrs, 40 units (brand new), 3 fails. Four installs per year, 7.5% failure rate, decent sample size.
In the last few years, I have installed one used Tri-Spark, and sold 3 Pazon units. zero reported failures so far./color]
Not quite as good, maybe. "Few" years. 4 units (brand new) no fails. But a very small sample size.
In nearly 30 years of working on classic Britbikes, I have removed more than 20 failed Boyer units. About 15 black box failures, the other 5 were stator failures. I have only dealt with 3 bikes that had Boyer units that DIDN'T fail, and I still have 1 of them.
This does not seem meaningful to me unless you know the total number of bikes that had Boyer and came in for other reasons. Or unless you're saying these 20 were also brand new and failed?
Either way, we can't determine the failure rate without the total, right? Are you saying that in 30 years, you only saw 23 bikes total with Boyers and that 20 of those failed, giving a failure rate of 87% ? Surely not.