We talk about octane, A/F ratio, and rpm ranges but lets not forget spark advance.
This is a SE stage 1 map (176AE106) of the front spark advance cylinder for a 2009 '96'. I can't prove it, but I would bet that this spark advance map is not any different from stock and what came on my 09 Dyna from the factory.
The lower the Map pressure number is, the lower the engine load is. 100 k/pa is max engine load.
Take a look at how much spark advance the engine has while at light engine loads (30-40 k/pa) while in the 2750 - 3000 RPM range (cell 40 X 2750). It is almost freighting. I did not make up these numbers. It is no wonder to me that there will be some sounds of detonation until the map sensor & ecm react and kick back the timing while at that same RPM (cell 90 X 2750). Its the same RPM but at two different map loads. Look at some of the cells that are in the 40's. Yes, they are in a much higher RPM range, but still an extreme number of degrees no engine could tolerate while under any real load. Shortly after you twist the grip, the ECM selects the cell it believes it needs based on the Map sensor. If that cell value can't do it, the Ion sensor kicks in and overrides that cell.
Cruising along, 2 up on flat ground (map @ 30) at 2750 RPM your probably in the 36 degrees of advance range....That is a bunch of advance. Then you crack the throttle. At that RPM you would need a map load of 80 k/pa to bring you back down to earth with your spark timing (80 k/pa).
It's easy to get carried away like I may have but it is important know how much spark advance your engine just may have.
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